Detection of acoustic velocity and electrical resistance tomographies for evaluation of peripheral-inner wood demarcation in urban royal palms

The material properties and thickness of peripheral wood of royal palms have significant impacts on in-situ structural safety. Stress wave velocity (V) and electrical resistance (ER) tomograms were detected in royal palms (Roystonea regia) for understanding the soundness and standard values of the peripheral region. The position of the peripheral-inner wood demarcation was measured using drilling resistance profile from living trees and the corresponding V and ER of the peripheral-inner wood boundary was acquired respectively from V and ER maps. The two parameters V and ER of the peripheral-inner wood demarcations were linearly related to the results obtained from tomogram. Furthermore, the positions of the peripheral-inner wood demarcation were determined by corresponding V and ER, and the critical V and ER can be established by average V and ER of tomographic data. The experimental results from this study indicated that V and ER tomogram techniques can be employed to determine the position of the peripheral-inner wood boundary and can serve as a technique to determine the structural stability status of living palms.