Yohei Kurata

Application of near infrared spectroscopy for estimating wood mechanical properties of small clear and full length lumber specimens

Near infrared (NIR) spectroscopy, coupled with multivariate analytic statistical techniques, has been used to predict the mechanical properties of solid wood samples taken from small clear and full length lumber specimens of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi). The specific mechanical characteristics evaluated were modulus of elasticity (MOE), modulus of rupture (MOR) in bending tests, maximum crushing strength in compression parallel to grain (CS), dynamic modulus of elasticity of air-dried lumbers (Efr), and wood density (DEN). Partial least squares (PLS) regression calibrations were developed for each wood property. The calibrations had relatively strong relationships between laboratory-measured and NIR-predicted values in small clear specimens, with coefficients of determination ranging from 0.61 to 0.89. The calibration models were applied to the prediction data sets and results suggested that NIR spectroscopy has the potential to predict mechanical properties of small clears with adequate accuracy (standardised prediction error=2.06-2.82). The PLS models based on spectra from the radial face (R2 = 0.73-0.89) of wood were slightly superior to those from the tangential face (R2 = 0.61-0.84). This might be due to the differences of the surface condition in terms of the anatomical structures and, thus, radial face better represents the sample. A reasonable predictive model for wood stiffness was also obtained from the full length lumber specimens, but the accuracy of the calibration for prediction was less than the small clear specimens (R2 = 0.49-0.78). The regression coefficients obtained from the PLS models showed similar trends in all mechanical properties. It was suggested that the absorption bands due to the OH-groups in cellulose were the major contributors to building robust models for predicting the mechanical properties of wood

Feasibility of Near-Infrared Spectroscopy for On-Line Grading of Sawn Lumber

Near-infrared (NIR) spectroscopy, coupled with multivariate analysis, has been used to evaluate the wood properties of sawn lumber of Japanese larch (Larix kaempferi), whose diffuse reflection spectra were acquired under static and moving conditions. Prediction models of the dynamic modulus of elasticity (Efr), the modulus of elasticity in bending tests (Eb), the bending strength (Fb), the wood density (DEN), and the moisture content (MC) were developed using partial least squares (PLS) analysis. For all wood properties, models obtained from data collected under the moving condition as an analogue of on-line measurement were superior to those from the static condition data. The regression coefficients for the PLS models predicting the mechanical properties in both static and moving conditions showed clear peaks at the absorption bands due to the three major polymers of wood, i.e., cellulose, hemicellulose, and lignin. NIR spectroscopy has high potential for the on-line grading of sawn lumber.

Feasibility of near-infrared spectroscopy for online multiple trait assessment of sawn lumber

Near-infrared (NIR) spectroscopy coupled with multivariate analysis was applied to estimate multiple traits of sawn lumber. The effects of the lumber conveying speed (LCS) and measurement resolution of spectra (MRS) on the calibrations were examined. NIR spectra ranging from 1300 to 2300 nm were acquired at LCSs of 10, 20, and 30 m/min and at MRSs of 2, 4, and 16 nm. Prediction models of bending strength (Fb), modulus of elasticity in bending tests (Eb), dynamic modulus of elasticity (Efr), and wood density (DEN) were developed using partial least-squares (PLS) analysis. LCS and MRS did not significantly influence the calibration performance for any wood property. The regression coefficients also showed no clear differences for any of the conditions. This indicates that the important explanatory variables included in the models are not greatly influenced by these measurement conditions. PLS2 analysis results, when presented graphically, allowed easy interpretation of the relationships between wood mechanical properties and chemical components, e.g., bending strength and stiffness were mainly related to polysaccharides cellulose and hemicellulose. NIR spectroscopy has considerable potential for online grading of sawn lumber, despite the harsh measurement conditions.

Optical characteristics of wood investigated by time-of-flight near infrared spectroscopy

Abstract A new optical measurement system, the main components of which are a diode-pumped solid state laser and avalanche photodiodes, was introduced to clarify the optical characteristics of wood from the viewpoint of time-of-flight near infrared spectroscopy. The sample thickness and the wavelength of input pulsed laser clearly influenced the transmitted time-resolved profile. The effective optical path length became 15 times longer than the sample thickness. The optical model based on the diffusion approximation to the radiative transfer equation proved to be useful for thick samples, which can be optically regarded as an ideal diffuser, although wood is a structural material with non-homogeneous cellular structure.

Application of Time-of-Flight Near-Infrared Spectroscopy to Fruits: Analysis of Absorption and Scattering Conditions of Near-Infrared Radiation Using Cross-Correlation of the Time-Resolved Profile

The absorption and scattering conditions of near-infrared radiation in a grapefruit, a popular thick-peeled fruit, were investigated by time-offlight near-infrared spectroscopy (TOF-NIRS). The cross-correlation function was introduced to obtain fine spectroscopic information from the time-resolved profile. Variation of the optical parameters in both the time-resolved profile and the cross-correlation function showed that the NIR radiation was largely absorbed in the peel and considerably scattered in the flesh of the fruit. It also reflected the straightness of the input pulsed laser. The substantial optical path length of the grapefruit estimated from the cross-correlation function was approximately 4 to 5 times as long as the nominal optical path length (NOPL). The cross-correlation function was an effective tool to analyze the absorption/scattering conditions of NIR radiation in a sample where an unstable light source such as a Nd:YAG laser with high output energy was employed.

Application of Time-of-Flight near Infrared Spectroscopy to Fruits—Permeability of Pulsed Laser Beam into Satsuma Mandarin, White Grapefruit and Fuji Apple

The permeability of a pulsed laser beam into Satsuma mandarin, White grapefruit and Fuji apple was compared by time-of-flight near infrared (ToF-NIR) spectroscopy. In this study, a compact measurement system including a dye-doped plastic laser cavity with a wavelength of 800 nm and an avalanche photodiode were employed. The NIR radiation attenuance (i.e. optical density) in apple was higher than in the citrus fruit. The peak maxima of transmitted radiation of intact Satsuma mandarin increased 130 times more than that of intact grapefruit. Differences in diameter related directly to attenuance. The peak maxima of transmitted radiation of peeled grapefruit increased 250 times more than that of intact grapefruit; however, these increases were not found for Satsuma mandarin or apple. NIR radiation attenuance of the grapefruit peel was greater than for the peel of the other fruits. The incident pulsed laser beam was uniformly scattered in the citrus sample, whereas the scattering condition of the pulsed laser beam in apple might not be uniform because of the presence of core tissue. Thus, while the pulsed laser beam could be transmitted through citrus fruit and apple, the effect of fruit size and peel on the NIR radiation attenuance characteristically varied.

Variation in Hemicellulose Structure and Assembly in the Cell Wall Associated with the Transition from Earlywood to Latewood in Cryptomeria japonica

The size of cellulose microfibril (CMF) bundles varies to interact with glucomannan/galactoglucomannan (GM/GGM). Arabino-4-O-methylglucuronoxylan (AGX) bonded CMF bundles coated with GM/GGM also have important roles in elaborating the distance between these components. Since the precise roles of GM/GGM and AGX are not clear, the elution analysis to evaluate the strength of the interaction between the cell wall were tried. Earlywood (EW) and latewood (LW) were separated in a Japanese cedar. The chemical components of cellulose, hemicellulose including GM/GGM and AGX, and lignin were almost the same in EW and LW. Slight differences in GM/GGM, the side-chain substitution in AGX and the ionic bond characteristics of glucuronic acid side chains were observed. Based on measurements of GM/GGM and AGX adhering to CMFs, there were more hemicelluloses forming strong hydrogen bonds in LW than in EW. The results showed that the highly assembled hemicellulose in LW produced a strong cell wall framework.

Nondestructive Classification Analysis of Wood Soaked in Seawater by Using Near-Infrared Spectroscopy

Abstract Large amounts of construction wood were generated as disaster waste during the 2011 Tōhoku, Japan, earthquake and tsunami. The construction wood waste had been immersed in seawater and thu...