José Tarcísio Lima

Robustness of models based on near infrared spectra to predict the basic density in Eucalyptus urophylla wood

Scientific contributions have shown good results by using near infrared (NIR) spectroscopy as a rapid and reliable tool for characterising lignocellulosic materials. Many reports have evaluated the predictive power and the robustness of the NIR models by means of methods known to validate them. However, in most of these investigations, the samples were divided systematically into two non-independent groups: one group was used to build and the other to validate the NIR models. This approach does not adequately simulate a real situation in which the properties of unknown samples should be predicted by established NIR models. Hence, the aim of this paper was to evaluate the robustness of models based on NIR spectroscopy to predict wood basic density in Eucalyptus urophylla using two totally independent sample sets. Wood density and NIR spectra were measured in diffuse reflectance mode on transversal, radial and tangential surfaces of wood samples in two data sets. We used one data set to build partial least squares regression (PLS-R) models and another to validate them and vice versa. The predictive models developed from the radial surface NIR spectra proved satisfactory with r2 p varying from 0.79 to 0.85 and RPD ranging from 2.3 to 2.7, while the spectra measured on tangential and transversal wood surfaces generated less robust regression models. Our results showed that it is possible to assess wood density in unknown samples by established PLS-R models from solid wood samples preferably using radial surfaces.

Genotype-environment interaction in wood basic density of Eucalyptus clones.

Summary Wood basic density was determined in samples taken from eight-year-old trees of 26 Eucalyptus clones growing in tests at four sites in Brazil. Within-clone variation in basic density was low. The broad sense heritability of basic density was 0.96 when estimated from five clones growing on two sites and 0.64 when estimated from 26 clones on four sites. Analysis of variance showed that there were significant differences in basic density between clones and sites, and that the clone × site interaction was also significant. Regression analysis was used to examine the stability of clones over environments. There were marked differences in stability between clones (linear regression coefficients 0.03 to 1.93). Interactions were variable (coefficients of determination zero to 93%), and in most cases it was not possible to predict the basic density of wood produced at one site from its value at another site. However, interactions accounted for less than 4% of the total variance in basic density; rank correlations between sites were all significant, and it was possible to identify clones which produced wood of consistently high or low basic density on the four test sites.

Propriedades e classificação da madeira aplicadas à seleção de genótipos de Eucalyptus

The objective of this study was to classify and select superior genotypes of eucalypt based on the properties of its wood, utilizing cluster analysis, the Tochers optimization method aiming to obtain various products. Forty-four genotypes adapted to the environmental conditions of northwestern Minas Gerais were used. Physical, mechanical resistance and chemical wood characteristics were used for the classification of the materials. Cluster analysis classified the genotypes in 11 different groups with high variability or divergence among them. According to the average values of the characteristics presented by the formed groups, it was possible to define new potential clones, which will certainly provide wood of superior quality. The genotypes from groups V, VI and VIII show potential for the production of sawed wood, also facilitating the generation of natural hybrids, which may be used in future programs of genetic improvement of Eucalyptus.

Resonance and near infrared spectroscopy for evaluating dynamic wood properties

Dynamic longitudinal (L) and transversal (T) tests based on wood resonance were performed on Eucalyptus specimens measuring 410 mm × 25 mm × 25 mm to obtain the dynamic elastic modulus (EL and ET), the first resonance frequency (f1L), the loss tangent (tan δT) and the specific modulus (E′L and E′T). Such dynamic traits and the air-dry density of wood were correlated by partial least squares (PLS) regressions to the near infrared (NIR) spectra measured in the central position of the longitudinal–radial surfaces. The statistics of the validation models for E, E′ and f1L ranged from 0.72 to 0.81 while the calibrations for loss tangent presented lower r2v (0.38), but promising RPD (ratio of performance to deviation) values (1.88). The key role of chemical wood components in the NIR-based calibrations for dynamic properties of wood is discussed. The association of the NIR spectroscopy and resonance techniques appears to be a rapid, low-cost and precise way to evaluate the visco-elastic properties of woods.

DEFORMAÇÕES RESIDUAIS LONGITUDINAIS DECORRENTES DE TENSÕES DE CRESCIMENTO EM EUCALIPTOS E SUAS ASSOCIAÇÕES COM OUTRAS PROPRIEDADES 1

RESUMO - Tensoes de crescimento representam um fator limitante para o uso do eucalipto de rapido crescimento como produtor de toras para serrar. A quantificacao e qualificacao dessas tensoes em arvores de Eucaliptos ainda carecem de muitas informacoes no Brasil. Assim, objetivou-se avaliar a aplicacao de um novo instrumento, o extensometro CIRAD-Foret, na medicao das deformacoes residuais longitudinais (DRL) em arvores de cinco materiais geneticos de Eucaliptos e correlaciona-las com outras caracteristicas da madeira e dimensoes das arvores. Dos resultados pode-se concluir que: i) o extensometro e simples de ser usado, rapido e confiavel para medir e identificar arvores com diferentes niveis de tensoes de crescimento; ii) a deformacao residual longitudinal (DRL), associada as tensoes de crescimento, medida com o extensometro foi em media igual a 71 µm; iii) nao foi encontrada diferenca estatistica nas DRLs medidas nas diferentes orientacoes cardeais em volta do tronco; iv) as DRLs variaram em funcao dos materiais geneticos de acordo com a analise de variância; v) em um dos materiais geneticos, no qual a DRL foi medida em duas posicoes ao longo do tronco (1,3 e 2,5 m), os valores foram semelhantes; vi) entre as varias propriedades da madeira, apenas a densidade basica foi correlacionada significativa e positivamente com a DRL quando todos os materiais geneticos foram analisados conjuntamente; vii) exceto para o fator de estabilidade (DAP/altura total) da progenie 5, as correlacoes entre as DRLs e as caracteristicas de crescimento das arvores nao foram significativas quando os materiais geneticos foram analisados isoladamente. Entretanto, quando os cinco materiais geneticos foram reunidos, apenas a altura total da arvore nao resultou em correlacao significativa com DRL; viii) a adicao de DRL as caracteristicas de crescimento das arvores permitiu que a densidade e as varias propriedades mecânicas da madeira fossem significativamente estimadas por modelos multiplos. ABSTRACT - Growth stresses are a limiting factor in the use of fast growing eucalypts for the production of sawing logs. Further studies are needed for the qualification and mensuration of these stresses in eucalypts trees in Brazil. Thus, the main objective of this work was to evaluate the application of a new instrument, CIRAD-Foret extensometer, in the measurement of the longitudinal residual strain (DRL) in standing trees of five genetic materials of eucalypts, experimentally cultivated in Aracruz-Espirito Santo, and to correlate the magnitude of such strain with other wood properties and tree dimensions. The results obtained showed that: i) the extensometer is a simple, rapid and reliable instrument to measure and identify trees with different levels of growth stresses; ii) the DRL associated to the growth stresses measured with the extensometer were in average equal to 71 µm; iii) no statistical differences were found in the DRLs measured in different cardinal orientations; iv) the DRLs varied significantly with the genetic material according to the analyses of variance; v) for clone 1, in which the DRLs were measured in two positions along the stem (1.3 m and 2.5 m), the values were similar; vi) among various wood properties, only basic density was positive and significantly correlated with the DRLs when the five genetic materials were analysed together; vii) except for the stability factor (DBH/total height) of variety 5, the correlation between DRL and the tree growth dimensions were not significant when the genetic materials were analyzed separately, however, when the five genetic materials were analyzed together, only total height of the tree did not result in significant correlation with the DRLs; viii) DRL addition to the tree growth dimensions allowed density and several wood mechanical properties to be significantly estimated by multiple models.

Influência das características tecnológicas na cor da madeira de eucaliptos.

Due to importance of the color of the wood as a component of its description this study was undertaken to verify the influence of chemical components in the color of wood of various clones of eucalypt. The amount of lignin and polyphenols in the wood, the fibres dimensions and its specific gravity were determined. The colorimetric measurements were made through a specterphotometer Data Color 200d Microflash. It was verified by the characteristics of the wood studied, that the amount of extractives, basically polyphenols, had high correlation with the color of the wood.

Near infrared spectroscopy for estimating Eucalyptus charcoal properties

Steel can be produced from vegetable charcoal used as a thermo reducer in steel blast furnaces. Hence, the metallurgical industry requires new solutions for controlling the quality of their charcoal in order to maintain the same quality standard. The objective of this study was to assess the properties of charcoal by near infrared spectroscopy. Partial least square (PLS) regressions were established for estimating fixed-carbon, volatile matter content and gravimetric yield of charcoal. These models were validated by cross-validations and independent test sets and presented similar performance. PLS-R models obtained from untreated NIR spectra for FCC and VMC yielded promissory statistics [r2p of ∼0.9; root mean squared error of prediction (RMSEP) of ∼3.3%; and ratio of the standard error of prediction to standard deviation (RPD)>3] while the statistics of the calibrations for gravimetric yield had relatively lower magnitude (R2p of ∼0.8, a RMSEP of ∼2.2 and RPD<2). Since new solutions are required for controlling the quality of charcoal with speed and precision, these models can be useful for monitoring charcoal quality in steel industries.

Clones de Eucalyptus versus a produção de polpa celulósica.

The wood quality is defined by combining several intrinsic characteristics of the tree to its use. This research aimed to evaluate some of the wood characteristics of Eucalyptus clones and its performance in kraft pulping. Fifteen clones, 5.8 years-old were used, two trees from each clone, totaling thirty trees. The evaluated wood characteristics were: basic density, fiber dimensions (fiber length, wall thickness, lumen diameter) and chemical composition (cellulose, lignin, hemicelluloses, extractives and ash contents). Four samples were cooked at the laboratory for each tree, using different active alkali, to establish the delignification curve. These alkali loads were selected after exploratory cooking to obtain an eighteen kappa number at the medium point of the curve. In the cooking were appraised the screened, the pulp viscosity and consumed alkali. The yield results varied from 43.4 to 52.0%, the active alkali from 17.5 to 23.4%, the consumed alkali from 15.5 to 20.0% and the pulp viscosity from 19.9 to 61.4 cP.

Air drying of logs from an Eucalyptus urophylla clone for carbonization use

A secagem da madeira e uma das etapas do processo de carbonizacao e seu controle e de grande importância no rendimento e na qualidade do carvao vegetal produzido. Nas empresas produtoras de carvao, apos o corte, a madeira e empilhada nas margens das estradas ou proxima aos fornos de carbonizacao e e carbonizada apos 90 dias de secagem ao ar livre, quando se deseja alcancar 30% de umidade. Neste trabalho, objetivou-se avaliar a secagem ao ar livre de toras de um clone de Eucalyptus urophylla empregado na producao de carvao vegetal, analisando-se a perda de umidade no tempo, influencia da casca e do diâmetro das toras no processo. Foram utilizadas toras com casca e sem casca, com diâmetros variando de 6,0 a 21,0 cm, densidade basica media de 0,496 g/cm3 e 3,60 m de comprimento, provenientes de um talhao comercial de Eucalyptus urophylla com 8 anos de idade. Pilhas de secagem ao ar livre foram instaladas em Paraopeba, Minas Gerais, Brasil e o acompanhamento da secagem foi realizado por pesagens periodicas das toras durante 80 dias. Ao final deste estudo, observou-se que as maiores perdas de umidade ocorreram nas tres semanas iniciais. A umidade das toras sem casca (54%) e com casca (50%) foram proximas apos 80 dias de secagem, com uma maior reducao de umidade para as toras sem casca. A influencia da casca na perda de umidade foi mais pronunciada nas tres primeiras semanas. A reducao de umidade ocorreu em intensidades diferentes em funcao do diâmetro das toras. Apos 80 dias, a maior reducao de umidade foi observada nas toras sem casca: 65% para as toras de maiores diâmetros e 80% para as de menores diâmetros. Ja, para as toras com casca os resultados foram respectivamente 56% e 75%.

Predicting moisture content from basic density and diameter during air drying of Eucalyptus and corymbia logs

In air drying of Eucalyptus urophylla and Corymbia citriodora logs for the production of charcoal it is necessary to be able to predict when logs have reached the required moisture content of ≤ 35%.This study is aimed to produce models using basic density and diameter to predict the moisture content of Eucalyptus urophylla and Corymbia citriodora logs after 30, 60 and 90 days drying. 1,2 m long logs were taken at three different heights from three C. citriodora trees and three trees each from two E. urophylla clones (VM4 and Mn463). The 27 debarked, end sealed logs were air dried under cover for 90 days during which the change in moisture content was monitored. The relationship between density and drying was analyzed by Pearson’s correlation coefficient and the models for predicting the moisture content based on the basic density and diameter were produced. The density and the drying showed a high correlation coefficient. The coefficient of determination of the models was above 0,89 with a standard error lower than 6%. The use of the density and diameter to estimate the wood moisture content simplifies the production of the models, which can be used for Eucalyptus and Corymbia genetic materials.