The physical properties of wood are important parameters to qualify the material. However, as it is a heterogeneous material, moisture content and wood contractions may vary within the sample. Thus, the objective was to monitor the hydromechanical behavior of wood during drying using near infrared (NIR) spectroscopy and image analysis. Equidistant points were marked on the radial surface of a wooden board and NIR spectra were recorded at each marking during drying of the piece. After spectral acquisition in each drying step, images were obtained and the markings were referenced to monitor contractions during drying. Moisture content (MC) estimates via NIR spectra showed strong correlation with reference values (R2cv = 0.92, RMSEcv = 9.82 %). From the estimates it was possible to generate graphic images to visualize and quantify the spatial variation of MC and shrinkage during wood drying. In the initial stages of drying, the ends of the material showed high moisture in relation to the center of the sample. However, MC loss was 11 % greater at the ends of the wood board when compared to its interior while the shrinkage in external zones was 3 times greater than the internal part. The use of NIR technique associated with image analysis can be a promising tool for estimating moisture contents and contractions in wood.

中文翻译：

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通过近红外光谱和图像分析研究木材干燥过程中的流体力学行为

木材的物理特性是衡量材料质量的重要参数。然而，由于它是一种异质材料，样品中的水分含量和木材收缩可能会有所不同。因此，我们的目标是利用近红外 (NIR) 光谱和图像分析来监测木材在干燥过程中的流体力学行为。在木板的径向表面上标记等距点，并在木板干燥期间记录每个标记处的近红外光谱。在每个干燥步骤中采集光谱后，获得图像并参考标记来监测干燥过程中的收缩。通过近红外光谱估算的水分含量 (MC) 显示与参考值 (R2cv = 0.92，RMSEcv = 9.82 %）。根据估计，可以生成图形图像来可视化和量化木材干燥过程中 MC 和收缩的空间变化。在干燥的初始阶段，材料的末端相对于样品的中心显示出较高的湿度。然而，与内部相比，木板端部的 MC 损失大 11%，而外部区域的收缩率是内部区域的 3 倍。使用与图像分析相关的近红外技术可以成为估计木材水分含量和收缩的有前途的工具。