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Prediction of MOR and MOE of structural plywood board using an artificial neural network and comparison with a multivariate regression model. Composites Part B: Engineering. 43(8): 3528-3533.



Abstract: The structural application of plywood boards has increased considerably in recent years. In this context, determining plywood mechanical properties such as bending strength and modulus of elasticity through predictive models using more-easily obtained properties is a very useful tool for in-factory quality control. Artificial neural networks have demonstrated their high capacity for modelling complex relations between variables, considerably improving on results obtained through regression techniques. Four neural networks were developed to obtain these mechanical properties by determining board thickness, moisture content, specific gravity, bending strength and modulus of elasticity of test pieces of small dimensions. The results were compared with those of a regression model and in all cases the results of the present study were better. 

 

Curves for the estimation of the wood moisture content of ten hardwoods by means of electrical measurements. Forest Systems. 21(1): 121-127.



Abstract: Accuracy in moisture content measurement is of great importance in the assurance of wood product quality and is necessary to meet administrative and normative requirements. Improving the accuracy of resistance-type moisture meters, and meeting the normative demands of their annual calibration, requires the use of optimised curves relating electrical resistance to moisture content for the most commercially important wood types. The Samuelsson model, adjusted by linear regression techniques, was used to describe the relationship between the electrical resistance and moisture content of seven boreal and three tropical hardwoods available on the Spanish market. The curves produced can be used to predict the moisture contents of these hardwoods via the measurement of their electrical resistance with an error of just ± 1.0%. These curves should also prove of great use in the calibration of wood resistance-type moisture meters.

 

Sorption and thermodynamic properties of cork from the 35ºC and 50ºC isotherms. Bois et Forêt des Tropiques. 311(1): 63-74.


Abstract: Because of its characteristics, cork currently has no substitute in the bottle stopper industry for high quality wines and champagnes. Few studies have been conducted on water-cork relations, particularly the thermodynamic behaviour of cork. The hygroscopicity and thermodynamic properties of two cork samples of the same quality, harvested in 1968 and 2006, were studied to determine any differences in behaviour caused by the passing of time. The 35ºC and 50ºC isotherms were plotted following the saturated salts method and fitted using the GAB model. The isotherms were compared through the hysteresis coefficients. The infrared spectra were recorded to study the chemical changes in the cell wall, and the thermodynamic parameters were determined using the integration method of the Clausius-Clapeyron equation. No significant differences were observed between the equilibrium moisture content obtained in the two samples, although the monolayer saturation moisture content was significantly lower in the older cork. In both types of cork, as occurs in wood, the points of inflexion where multilayer sorption begins to predominate over monolayer sorption occurred at very similar values, around 31-35% RH. In terms of the thermodynamic properties, the net isosteric heat curves were similar to those obtained in wood, and the bond energy in the recently harvested cork was lower than in the older cork.

Physico-mechanical characterisation of Abies alba Miller wood from the Spanish Pyrenees using clear specimens. Informes de la Construcción. 65 (530): 213-218.



Abstract: This study provides up-to-date, representative values of the physical and mechanical properties of silver fi r wood from the Spanish Pyrenees for comparison with other provenances and timber species. Tests were conducted with clear specimens obtained throughout the tree stem and properties were determined following the UNE standards of the corresponding tests. The wood was found to be light (ρ= 0.48 g/cm3), soft (H=1.71 mm-1) and moderately stable (v=39.43%). Its bending strength (MOR=78.70 N/mm2) is low and its compressive strength (MCS=44.88 N/mm2) is average. Impact behaviour is average (K=41.46 N/mm) and cleavage behaviour (C=19.92 N/mm) is low, as are tangential and radial tension perpendicular to the grain (1.71 and 1.68 N/mm2). The differences obtained in comparison with other provenances of this species may be the result of the location of the silver fi rs at the edge of their geographical distribution and thus the specifi c conditions of the site have a greater effect on the wood properties.

 

Variation throughout the tree stem in the physical-mechanical properties of the wood of Abies alba Mill. from the Spanish Pyrenees. Madera y bosques. 19(2): 87-107



Abstract: This study analyses the variation of main physical-mechanical properties of wood along the longitudinal and radial directions of the tree for Abies alba Mill. growing in the Spanish Pyrenees. Small clear specimens were used to study the properties of volumetric shrinkage (VS), density (.), hardness (H), bending strength (MOR), modulus of elasticity (MOE), maximum compressive strength parallel to the grain (MCS) and impact strength (K). Several models of properties variation in the longitudinal and radial directions were analyzed. Main trends of variation of properties throughout the tree stem were identified although none of them could be fitted to predictive statistical models. Along the longitudinal direction, the properties studied followed a downward trend from the base to the crown, which was not significant in all cases, indicating that no differences in quality existed. Throughout the radial direction the trend is upward for the first 40-50 growth rings, after which it slopes downwards, more gently at first until rings 70-75 and then more steeply. This behaviour is related to variation in wood structure from the pith to the bark, depending on whether the wood is juvenile, sapwood or heartwood, and to wood maturity and microfibril angle. Authors encourage carrying further studies on other populations of A. alba in the Spanish Pyrenees to check if the trends found in this study apply to other provenances.

 

Gonzalez-Rodrigo, B.

Esteban, L. G.

de Palacios, P.

Garcia-Fernandez, F.

Guindeo, A.


2013

González Rodrigo, B.

Esteban, L.G.

de Palacios, P.,

García Fernández, F.

Guindeo, A.


2013

40

39

García Fernández, F.

de Palacios, P.

Esteban, L.G.

García-Iruela, A.

González-Adrados, J.R.

López Alvarez, J.V.


2012

38

Fernández-Golfín, J.I.

Conde García, M.

Conde García, M.

Fernández-Golfín, J.J.

Calvo Haro, R.

Baonza Merino, M.V.

de Palacios, P.


2012

37

García Fernández, F

de Palacios, P.

Esteban, L.G.

García-Iruela, A.,

González Rodrigo, B.

Menasalvas, E.


2012

36

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