Department of Agro-Environmental Science, Faculty of Agriculture, Kyushu Univ., 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan.
Ultrasonics. 2011 Apr;51(3):296-302. doi: 10.1016/j.ultras.2010.10.001. Epub 2010 Oct 14.
The radial variations in the velocity of longitudinal waves propagating through Japanese cedar and Japanese cypress were experimentally investigated. In addition, the tracheid length (TL), microfibril angle (MFA), air-dried density (AD), and moisture content (MC) were measured in order to determine the effect of wood properties on velocity variations within the wood trunk. For both species, the longitudinal wave velocities measured in the longitudinal direction (V(L)) exhibited minimum values near the pith. For Japanese cedar, V(L) increased from 3600m/s toward the bark and soon attained a constant value (=4500m/s). On the other hand, for Japanese cypress, V(L) kept increasing from 4000m/s near the pith to 4800m/s at the bark. These radial variations in V(L) coincided with those in the tracheid length. V(L) exhibited strong correlations with TL and MFA with a significant level of (p<0.01). These findings suggest that the TL and MFA greatly affect the radial variation in the ultrasonic wave velocity in softwood.
对通过日本扁柏和日本柳杉传播的纵波速度的径向变化进行了实验研究。此外，还测量了管胞长度（TL）、微纤丝角（MFA）、气干密度（AD）和含水率（MC），以确定木材性质对树干内速度变化的影响。对于这两个物种，在纵向方向上测量的纵波速度（V（L））在髓心附近呈现最小值。对于日本扁柏，V（L）从 3600m/s 向树皮方向增加，并很快达到恒定值（=4500m/s）。另一方面，对于日本柳杉，V（L）从髓心附近的 4000m/s 持续增加到树皮处的 4800m/s。这些 V（L）的径向变化与管胞长度的变化一致。V（L）与 TL 和 MFA 具有很强的相关性，具有显著的（p<0.01）水平。这些发现表明，TL 和 MFA 极大地影响了软木中超声波速度的径向变化。
