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Search Results: 1 - 10 of 37620 matches for " Paulo Ricardo Gherardi Hein "
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Relationships between microfibril angle, modulus of elasticity and compressive strength in Eucalyptus wood
Gherardi Hein,Paulo Ricardo; Tarcísio Lima,José;
Maderas. Ciencia y tecnología , 2012, DOI: 10.4067/S0718-221X2012005000002
Abstract: many traits are known to be important in determining the value of eucalyptus wood as sawn timber. the commercial importance of the microfibril angle (mfa) for wood quality is well established for a range of softwoods, but is less clear for hardwood species. for instance, the relationships of mfa with wood stiffness and compressive strength are unknown in eucalyptus. therefore, the aim of this study was to evaluate the correlation between mfa and the modulus of elasticity (ec0,m) in compression parallel to grain and compressive strength (fc0,k) using juvenile wood of eucalyptus grandis from fast-growing plantations. the correlation between wood stiffness and compressive strength was high (0.91). the cellulose microfibril angle presented a correlation of -0.67 with wood stiffness and of -0.52 with compressive strength in eucalyptus juvenile wood. mfa was found to be important in determining the mechanical behaviour of wood and appears to be a useful parameter to indicate wood stiffness and strength in juvenile eucalyptus from short-rotation plantations.
Relationships between microfibril angle, modulus of elasticity and compressive strength in Eucalyptus wood
Paulo Ricardo Gherardi Hein,José Tarcísio Lima
MADERAS : Ciencia y Tecnología , 2012,
Abstract: Many traits are known to be important in determining the value of Eucalyptus wood as sawn timber. The commercial importance of the microfibril angle (MFA) for wood quality is well established for a range of softwoods, but is less clear for hardwood species. For instance, the relationships of MFA with wood stiffness and compressive strength are unknown in Eucalyptus. Therefore, the aim of this study was to evaluate the correlation between MFA and the modulus of elasticity (Ec0,m) in compression parallel to grain and compressive strength (Fc0,k) using juvenile wood of Eucalyptus grandis from fast-growing plantations. The correlation between wood stiffness and compressive strength was high (0.91). The cellulose microfibril angle presented a correlation of -0.67 with wood stiffness and of -0.52 with compressive strength in Eucalyptus juvenile wood. MFA was found to be important in determining the mechanical behaviour of wood and appears to be a useful parameter to indicate wood stiffness and strength in juvenile Eucalyptus from short-rotation plantations.
RADIAL VARIATION OF MICROFIBRIL ANGLE AND WOOD DENSITY AND THEIR RELATIONSHIPS IN 14-YEAR-OLD Eucalyptus urophylla S.T. BLAKE WOOD
Paulo Ricardo Gherardi Hein,Lo?c Brancheriau Mail
BioResources , 2011,
Abstract: The orientation of cellulose microfibrils in the cell wall along the stem axis has major effects on stiffness and longitudinal shrinkage and is of key importance in wood quality. The aim of this study was to investigate the radial variability of MFA and wood density (ρ) and their relationships in Eucalyptus urophylla wood. Three MFA values were estimated by X-ray diffraction at three points of each one of the 175 tangential sections, and the basic density was measured. A decrease of microfibril angles from pith to bark can be observed in most samples; however, some radial strips presented different patterns of variation. For basic density, a linear significant increase from pith to bark was confirmed. There was no significant correlation between microfibril angle and density. The relationships among the three MFA estimated on tangential sections of wood were strong. The “curvature effect” due to the growth rings had a negligible effect on the three measurements of tangential sections cut near to the pith. This study showed that a single T value measurement by X-ray diffraction, preferably at the centre of the tangential section, is precisely sufficient to estimate the mean MFA of Eucalyptus urophylla wood.
Predicting the morphological characteristics and basic density of Eucalyptus wood using the NIRS technique
Lívia Cássia Viana,Paulo Fernando Trugilho,Paulo Ricardo Gherardi Hein,José Tarcísio Lima
CERNE , 2009,
Abstract: This work aimed to apply the near infrared spectroscopy technique (NIRS) for fast prediction of basic density and morphological characteristics of wood fibers in Eucalyptus clones. Six Eucalyptus clones aged three years were used, obtained from plantations in Cocais, Guanh es, Rio Doce and Santa Bárbara, in Minas Gerais state. The morphological characteristics of the fibers and basic density of the wood were determined by conventional methods and correlated with near infrared spectra using partial least square regression (PLS regression). Best calibration correlations were obtained in basic density prediction, with values 0.95 for correlation coefficient of cross validation (Rcv) and 3.4 for ratio performance deviation (RPD), in clone 57. Fiber length can be predicted by models with Rcv ranging from 0.61 to 0.89 and standard error (SECV) ranging from 0.037 to 0.079 mm. The prediction model for wood fiber width presented higher Rcv (0.82) and RPD (1.9) values in clone 1046. Best fits to estimate lumen diameter and fiber wall thickness were obtained with information from clone 1046. In some clones, the NIRS technique proved efficient to predict the anatomical properties and basic density of wood in Eucalyptus clones.
Near infrared spectroscopy for estimating wood basic density in Eucalyptus urophylla and Eucalyptus grandis
Paulo Ricardo Gherardi Hein,Ana Carolina Maioli Campos,Paulo Fernando Trugilho,José Tarcísio Lima
CERNE , 2009,
Abstract: Wood basic density is indicative of several other wood properties and is considered as a key feature for many industrialapplications. Near infrared spectroscopy (NIRS) is a fast, efficient technique that is capable of estimating that property. However,it should be improved in order to complement the often time-consuming and costly conventional method. Research on woodtechnological properties using near infrared spectroscopy has shown promising results. Thus the aim of this study was to evaluatethe efficiency of near infrared spectroscopy for estimating wood basic density in both Eucalyptus urophylla and Eucalyptus grandis.The coefficients of determination of the predictive models for cross validation ranged between 0.74 and 0.86 and the ratio performanceof deviation (RPD) ranged between 1.9 and 2.7. The application of spectral filter, detection and removal of outlier samples, andselection of variables (wavelength) improved the adjustment of calibrations, thereby reducing the standard error of calibration (SEC)and cross validation (SECV) as well as increasing the coefficient of determination (R2) and the RPD value. The technique of nearinfrared spectroscopy can therefore, be used for predicting wood basic density in Eucalyptus urophylla and Eucalyptus grandis.
NEAR INFRARED SPECTROSCOPY FOR ESTIMATING SUGARCANE BAGASSE CONTENT IN MEDIUM DENSITY FIBERBOARD
Ugo Leandro Belini,Paulo Ricardo Gherardi Hein,Mario Tomazello Filho Mail,José Carlos Rodrigues
BioResources , 2011,
Abstract: Medium density fiberboard (MDF) is an engineered wood product formed by breaking down selected lignin-cellulosic material residuals into fibers, combining it with wax and a resin binder, and then forming panels by applying high temperature and pressure. Because the raw material in the industrial process is ever-changing, the panel industry requires methods for monitoring the composition of their products. The aim of this study was to estimate the ratio of sugarcane (SC) bagasse to Eucalyptus wood in MDF panels using near infrared (NIR) spectroscopy. Principal component analysis (PCA) and partial least square (PLS) regressions were performed. MDF panels having different bagasse contents were easily distinguished from each other by the PCA of their NIR spectra with clearly different patterns of response. The PLS-R models for SC content of these MDF samples presented a strong coefficient of determination (0.96) between the NIR-predicted and Lab-determined values and a low standard error of prediction (~1.5%) in the cross-validations. A key role of resins (adhesives), cellulose, and lignin for such PLS-R calibrations was shown. PLS-DA model correctly classified ninety-four percent of MDF samples by cross-validations and ninety-eight percent of the panels by independent test set. These NIR-based models can be useful to quickly estimate sugarcane bagasse vs. Eucalyptus wood content ratio in unknown MDF samples and to verify the quality of these engineered wood products in an online process.
NEAR INFRARED SPECTROSCOPY TO EVALUATE COMPOSITION OF AGRO-BASED PARTICLEBOARDS
Ana Carolina Maioli Campos,Paulo Ricardo Gherardi Hein,Lourival Marin Mendes,Rafael Farinassi Mendes
BioResources , 2009,
Abstract: Particleboards can be manufactured from particles of any lignin-cellulosic material that can be combined with an adhesive and consolidated under the action of temperature and pressure. Because the raw materials in the industrial process are continually changing, the particleboard industry requires methods for monitoring the quality of their products. Hence, the aim of this paper was to evaluate the composition of the agro-based particleboards by near infrared spectroscopy. In this study, agro-based particleboards produced with different compositions of Eucalyptus and Pinus wood particles and sugar cane bagasse were evaluated by NIR spectroscopy and partial least square (PLS) regression. The PLS models to estimate the Eucalyptus and Pinus particles and sugar cane bagasse contents presented a strong coefficient of determination (0.90, 0.88 and 0.84, respectively), but also high magnitudes of standard errors of cross-validation were observed (ranging from 8.84 to 11.27%). Development work would be required in order to reduce the standard errors and improve predictive model performance to build robust models that could be applied as quality control tool.
CALIBRATIONS BASED ON NEAR INFRARED SPECTROSCOPIC DATA TO ESTIMATE WOOD-CEMENT PANEL PROPERTIES
Paulo Ricardo Gherardi Hein,Vania Aparecida de Sá,Lina Bufalino,Lourival Marin Mendes
BioResources , 2009,
Abstract: Some scientific contributions have used near infrared (NIR) spectroscopy as a rapid and reliable tool for characterizing engineered wood products. However, to our knowledge, there are no published papers that used this technique in order to evaluate wood-cement panels. The main objective of this paper was to evaluate the ability of NIR spectroscopy to estimate physical and mechanical properties in wood-cement panels. The wood-cement panels were produced using Eucalyptus grandis x E. urophylla, Pinus taeda, and Toona ciliata woods with Portland cement under different manufacturing conditions. Wood-cement panels were characterized by traditional methods, and Partial Least Squares regressions were used to build calibrations. Our cross-validated models for MOR, IB, and TS24h of the panels yielded good coefficients of determination (0.80, 0.82, and 0.91, respectively). Based on the significant absorption bands and regression coefficients of the PLS models, our results indicate that cellulose and aromatic groups in lignin are components that play an important role in the calibrations.
Use of near infrared spectroscopy to distinguish carbonization processes and charcoal sources
Thiago Campos Monteiro,Renato Vieira da Silva,José Tarcísio Lima,Paulo Ricardo Gherardi Hein
CERNE , 2010,
Abstract: The near infrared spectroscopy (NIRS) has shown a rapid and accurate technique for evaluation of materials ofbiological origin. The objective of this study was to evaluate the ability of the near infrared (NIR) spectroscopy associated to thePrincipal Component Analysis (PCA) for the separation of carbonization processes and identification of the origin of the woodsused in the carbonizations. Hence, the charcoal of seven species of Eucalyptus and twenty native species from the Cerrado(savannah) of Minas Gerais, Brazil were investigated. The Eucalyptus wood was carbonized in a laboratory furnace and in a 190m3 industrial rectangular kilns while the wood of native vegetation was carbonized only under laboratory conditions. The sampleswere grinded for NIR spectra acquirement. The NIR spectra were analyzed by PCA but no cluster were identified allowingdiscrimination between charcoal produced from native and from Eucalyptus wood. However, the cluster formed in the PCA whenusing the first derivative NIR spectra permitted to distinguish charcoal produced in different processes of carbonization. Twogroups of data for charcoal produced in the industrial rectangular kilns were also observed, suggesting heterogeneity in thecarbonization process.
SMALL WOODEN OBJECTS USING EUCALYPT SAWMILL WOOD WASTE
Renato da Silva Vieira,José Tarcísio Lima,José Reinaldo Moreira da Silva,Paulo Ricardo Gherardi Hein
BioResources , 2010,
Abstract: Forest industries look for multiple utilizations for their timber production. In Brazil, the genus Eucalyptus has a great potential for solid wood products; however, only a small amount of Eucalyptus is used as sawn timber. About 50% of the log volume ends up as waste during mechanical processing, resulting in serious economic and environmental problems. In most cases, such residue is discarded at random or used as fuel, and in this context the sustainable management of processing industrial waste is an urgent necessity. Parallel to this, Eucalyptus has not been employed for small wooden object (SWO) production. Hence, the aim of this work was to evaluate the performance of small wooden objects produced with Eucalyptus urophylla, E. camaldulensis, and E. grandis waste from sawmilling. Brazilian craftsmen manufactured SWOs with Eucalyptus, and these crafted objects were presented at exhibits and trade fairs for assessment. The proposed small wooden objects made with Eucalyptus residues exhibited satisfactory performance and achieved excellent acceptance by the visitors. This work gave evidence that the use of sawmill waste as raw material for small wooden object manufacture has potential to generate income for economically underprivileged communities near to a plantation.
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