木材径切面内部缺陷的应力波成像算法

A stress wave tomography algorithm for internal defects in radial and longitudinal(RL) planes of wood

为了获得木材径切面上的缺陷形状、大小和位置,提出一种木材径切面内部缺陷成像的方法。首先,基于应力波在木材径切面上的传播规律,提出一种木材径切面上的应力波速度修正方法。将应力波速度转换为径切面上的若干个预估点的值,结合反距离加权插值(IDW)法提出一种速度修正插值(VCI)方法。最后,使用VCI方法在不同树木样本上进行了木材径切面缺陷的二维成像实验。结果表明:①VCI方法可以重建木材内部缺陷大小以及缺陷位置,缺陷成像结果与真实的缺陷情况相吻合。②对比IDW方法的成像结果, VCI方法对缺陷的大小以及缺陷形状、位置的成像结果有较大提高。③利用混淆矩阵方法对VCI与IDW方法进行定量分析表明, VCI方法的平均准确率、平均精确度和平均查全率均高于IDW方法,说明VCI方法成像效果的可行性和有效性。

To generate and obtain the shape,size,and position of defects in the radial and longitudinal(RL)planes of wood,this study presented a new method for imaging defects on the RL planes in wood.First,based on the propagation law of stress waves for the RL planes of wood,a modified method of propagating the velocity of stress waves was proposed.Then the propagation velocity of the stress wave was converted into a value at estimated points.Finally,a velocity correction interpolation method(VCI)was proposed to reconstruct any defects in different tree samples.Imaged results were then compared to the inverse distance weighted(IDW)interpolation method and quantitatively analyzed using the method of confusion matrix.Experimental results showed that(1)the proposed method could reconstruct the size of the internal wood defects and their location with imaging results of the defects being basically consistent with real defects.(2)Compared to imaged results from IDW,the proposed method has higher accuacy rate when reconstructing the size,shape,and location of the defect.(3)The quantitative analyses showed that the proposed method improved in average accuracy,average precision,and the average recall.Thus,imaged results of defects with different shapes showed the effectiveness of the proposed method in reconstruction defects in RL plans of wood.[Ch,6 fig.5 tab.17 ref.]