Wood Density Determination by X- and Gamma-Ray Tomography

Macedo, Álvaro; Vaz, C. M. P.; Pereira, J. C. D.; Naime, J. M.; Cruvinel, P. E.; Crestana, Sı́lvio

doi:10.1515/hf.2002.082

Cited by 31 publications

(25 citation statements)

References 18 publications

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“…Few deviations were found in function of position, indicating a very homogenous shell structure. The average density was 0.688 ± 0.057 gcm -3 close to values of eucalyptus wood as measured by Wimmer et al, (2002) and by Macedo et al, (2002). Concerning water absorption, the resultant gain of mass as a function of time is presented in Figure 5.…”

Section: Resultssupporting

confidence: 75%

An evaluation of fibrous structure and physical characteristics of Cutia nut (Couepia edulis Prance) shell

Assis¹,

Pessoa

2009

Acta Amaz.

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The Cutia-nut (Couepia edulis Prance), a species originally from the Amazon region, has a kernel with reasonable nutritional value and a hard and thick woody shell that constitute most of the fruit. After the kernel removal, the shells are regarded as waste. The possibility of using such shells, as raw material for burning or charcoal production, as well as milled residue for structural reinforcement materials is quite feasible, considering environmental and economical aspects. There is, however, a complete lack of characterization of the Cutia-nut shell and other similar species which can aggregate desirable qualities for application as engineering material. in this study some analyses are presented aiming at providing information for potential uses of these residues. in general, the shells follow a regular shape with certain dimensional proportionality to the kernel. The shell is a fibrous material with high lignin content, present low water absorption and high resistance to natural degradation.KEYWOrDs: Cutia-nut, shell characterization, fibrous structure, natural waste utilization Uma avaliação da estrutura fibrosa e das características físicas da casca da Castanha de cutia (Couepia edulis Prance) rEsumO A castanha-de-cutia (Couepia edulis Prance), uma espécie típica da região amazônica, é possuidora de uma amêndoa de razoável valor nutricional e caracterizada por ter uma casca espessa e altamente resistente, que constitui a maior parte do fruto. esta casca, após a retirada da amêndoa, é totalmente descartada. A possibilidade do aproveitamento das cascas, seja como matéria prima para a queima ou simples confecção de carvão, ou como elemento para uso como aditivo de reforço em materiais estruturais é plenamente viável, não somente do ponto de vista ambiental mas também econômico. Há, contudo, uma ausência total de caracterizações da casca da castanha-de-Cutia e de demais espécies tropicais similares que potencialmente podem agregar qualidades desejadas para aplicações como materiais de engenharia. Neste trabalho são apresentadas algumas análises realizadas que podem vir a subsidiar o potencial emprego desses resíduos. De um modo geral, as cascas apresentam formatos regulares com certa proporcionalidade dimensional com a amêndoa. são fibrosas e com alto teor de lignina o que garante baixa absorção de água e alta resistência à degradação natural.PALAVrAs-cHAVE: Castanha de Cutia, caracterização da casca, estrutura fibrosa, usos de resíduos naturais

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Section: Resultssupporting

confidence: 75%

An evaluation of fibrous structure and physical characteristics of Cutia nut (Couepia edulis Prance) shell

Assis¹,

Pessoa

2009

Acta Amaz.

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“…It is known (e.g. Macedo et al, 2002) that at low energies, variations in the chemical composition of the material cause variations in the linear attenuation coefficient even for materials having the same density. At high energies, the density influence prevails.…”

Section: Discussionmentioning

confidence: 99%

“…As we worked with averaged Hounsfield numbers computed from wood volumes, our results were not affected by these noise differences. Macedo et al (2002) proposed a completely different approach of calibration, performed directly on the mass attenuation coefficients (i.e. without using Hounsfield numbers which are normally computed from the attenuation coefficients), to estimate wood density with different types of X-and Gamma-ray scanners (but not with a medical one).…”

Section: Discussionmentioning

confidence: 99%

“…IV). An improvement in comparison with the previous studies (except Macedo et al, 2002) is that we used an independent data set for the statistical validation of our models.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, the Hounsfield numbers measured on air were shown to depend on the scanner model and settings and on the scan date, even for recently manufactured devices (Parr et al, 2004). Moreover, for low energies, differences in atomic composition may lead to differences in X-ray attenuation even for objects of the same density (Macedo et al, 2002). Since the atomic composition of wood may differ strongly from the material used for CT calibration, it appears important to calibrate the device specifically for the estimation of wood density ρ.…”

Section: Introductionmentioning

confidence: 99%

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Mesure de la densité du bois par tomographie à rayons X

Freyburger¹,

Longuetaud²,

Mothe³

et al. 2009

Ann. For. Sci.

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Abstract• Wood density is a characteristic of major interest. Usually, it is used as an indicator of wood quality; however, in the context of global change, it is increasingly used for biomass and carbon storage estimations. X-ray computer tomography is a method which enables quick estimates of wood density after applying a calibration procedure.• A review of the literature is presented in this article. Most of the previous studies have been performed in the 80's or at the beginning of the 90's.• In this study, the relationship between wood density and Hounsfield numbers was investigated using a recent medical scanner. A linear relationship was fitted using a calibration data set which consisted in tropical wood samples representing a large range of densities ranging between 133 and 1319 kg m −3 , and then validated using an independent data set (mainly temperate tree species). The fitted relationships were very strong (R 2 > 0.999), whichever the tested scanner settings, with slight but significant effects of the current voltage and reconstruction filters. The RMSE values computed from the validation data set ranged between 5.4 and 7.7 kg m −3 for densities ranging between 364 and 821 kg m −3 .• In conclusion, this method of calibration enables the use of a medical scanner to obtain maps of wood density, in a fast and non destructive way, and with a very good accuracy. Very interesting perspectives are opened regarding biomass distribution within trees. Mots-clés :densité du bois / tomographie à rayons X / CT / nombres Hounsfield / calibration Résumé -Mesure de la densité du bois par tomographie à rayons X.• La densité du bois est une caractéristique d'intérêt majeur. Généralement, elle est utilisée comme un indicateur de la qualité du bois ; cependant, dans le contexte du changement global, elle est de plus en plus utilisée pour des estimations de biomasse et de stockage de carbone. La tomographie à rayons X est une méthode permettant des estimations rapides de la densité du bois moyennant une procédure de calibration.• Une revue de la littérature sur le sujet est présentée dans cet article. La plupart des études précé-dentes ont été réalisées dans les années 80 ou au début des années 90.• Dans cette étude, la relation entre la densité du bois et les nombres Hounsfield a été étudiée en utilisant un scanner médical récent. Une relation linéaire a été ajustée sur un jeu de données de calibration constitué d'échantillons de bois tropicaux représentant une large gamme de densités allant de 133 à 1319 kg m −3 , et validée sur un jeu de données indépendant (principalement des essences tempérées). Les relations ajustées étaient très fortes (R 2 > 0.999) quels que soient les réglages utilisés pour le scanner, avec des effets légers mais significatifs de la tension d'accélération et des filtres de reconstruction. Les valeurs des RMSE calculées à partir de l'échantillon de validation sont comprises entre 5.4 et 7.7 kg m −3 pour des densités allant de 364 à 821 kg m −3 .• En conclusion, la méthode de calibration proposée...

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Application areas of synchrotron radiation tomographic microscopy for wood research

et al. 2009

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Possible applications for synchrotron radiation tomographic microscopy in the field of wood research were tested and evaluated at the TOMCAT beamline (TOmographic Microscopy and Coherent rAdiology experimenTs) at the Swiss Light Source (SLS) at the Paul Scherrer Institute (Villigen, Switzerland). For this study, small cylindrical samples ([ 1 and 3 mm) were examined with different experimental setups resulting in a nominal voxel size of approximately 1.48 9 1.48 9 1.48 and 3.7 9 3.7 9 3.7 lm 3 , respectively. Suitability of the TOMCAT microscope for 3D investigations of wood anatomy was tested on several softwood and hardwood species revealing microscopic features (e.g. tyloses, wall thickenings or pits) down to the nominal pixel size. The results suggest that even features in the sub-voxel range can be made visible. Tomographic microscopy was also tested for wood technological applications, i.e. penetration behaviour of a wood preservative and also of three wood adhesives (poly-urethane resins) with different viscosities. Although the experiments with the preservative yielded no clear results, the method seems suitable for examining the penetration of the different adhesives. The adhesive penetrates the wood mainly by the vessels where it can be easily discerned from the wood structure.

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Wood Density Determination by X- and Gamma-Ray Tomography

Cited by 31 publications

References 18 publications

An evaluation of fibrous structure and physical characteristics of Cutia nut (Couepia edulis Prance) shell

An evaluation of fibrous structure and physical characteristics of Cutia nut (Couepia edulis Prance) shell

Mesure de la densité du bois par tomographie à rayons X

Application areas of synchrotron radiation tomographic microscopy for wood research

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