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Evaluation of wood variation based on the eigenvalue distribution of near infrared spectral matrix
摘要： A method to evaluate the wood variation based on the eigenvalue analysis for the near infrared spectral matrix is presented. The set of eigenvalues calculated from the variance-covariance matrix is treated as the Hamiltonian, which represents the energy eigenstate of the wood, and the wood variation is discussed from the viewpoints of thermodynamics and statistical mechanics. To determine the validity of this idea, two sample groups, one having a high and the other having a low modulus of elasticity (Efr), are prepared, because they obviously have different molecular configurations in the cell wall. The eigenvalues of the high Efr group are widely distributed compared with those of the low Efr group. The probability corresponding to each energy eigenstate of the low Efr group is flatly distributed compared with that of the high Efr group. These results indicate that the low Efr wood has a more disordered structure than the high Efr wood. The Helmholtz free energy is higher in the high Efr group; in contrast, the entropy is higher in the low Efr group. The results obtained in this study are consistent with the previous knowledge with regard to the relationship between the mechanical properties and the microscopic structure of wood. Hence, the eigenvalues obtained from the NIR spectral matrix provide useful information to assess the variation and stability of wood.
关键词： information statistical mechanics,random matrix,Wood variation,eigenvalue distribution,modulus of elasticity
更新于2025-09-04 15:30:14
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Correlation of Near Infrared Spectroscopy Measurements with the Surface Roughness of Wood
摘要： The surface roughness of Chinese fir and Eucalyptus wood samples were measured using the stylus profile method in order to investigate the correlation between near infrared (NIR) spectroscopy and surface roughness. The results showed that the NIR spectra absorption showed differences among samples from different surface roughnesses, and the absorption decreased with the increase of the surface roughness. A strong relationship was found between the surface roughness parameters, i.e., the arithmetical mean deviation of the profile (Ra), the ten-point height of irregularities (Rz), and the maximum height of profile (Ry). Based on the NIR spectra of the Chinese fir wood samples and the mixed wood samples of the two wood species, and the correlation coefficients of these two types of wood samples in a calibration set were 0.77 to 0.83 and 0.67 to 0.74, respectively. A relatively poor correlation was found in the model based on the Eucalyptus samples; however, it was still significant. These results suggested that there was relative information about the surface roughness from the NIR spectra, which further illustrated that the surface roughness may influence the effect of models for wood properties built by NIR data.
关键词： Near infrared spectroscopy,Correlation,Wood,Surface roughness
更新于2025-09-04 15:30:14