Improvement of Wood CT Images by Consideration of the Skewing of Ultrasound Caused by Growth Ring Angle
Keywords:Ultrasonic wave, computed tomography (CT), transmission path, skewing effect, wave refraction, juvenile wood
AbstractFor the purpose of removing distortions in ultrasonic computerized tomographic (CT) images of wood, this study proposes a technique for taking into account the skewing effect in reconstructing the image. First, it was experimentally confirmed that an ultrasonic wave is refracted because of the anisotropic characteristics of wood. Transmission paths of an ultrasonic wave through a cross-section of wood were predicted by considering the change in wave velocity based on the annual ring angle and the presence of juvenile wood. Then, the methodology of the application of the predicted paths to CT image reconstruction was proposed and verified. The accuracy of defect detection in wood was significantly improved by the proposed technique.
Adachi K, Tamura Y, Hayashi K (1994) Cross-sectional imaging of wooden pillars with ultrasonic time-of-flight CT. Pp 279-284 in Proc. 29th International Symposium on Archaeometry. Ankara, Turkey.nAdachi K, Tamura Y, Hayashi K, Kanda S, Shioya K, Yamashita Y (1999) Development of ultrasonic time-of-flight computed tomography system for structural inspection of buildings. Technical Report of IEICE, US99-9. The Institute of Electronics Information and Communication Engineers. Pp 7-14.nBiernacki JM, Beall FC (1993) Development of an acoustic-ultrasonic scanning system for nondestructive evaluation of wood and wood laminates. Wood Fiber Sci 25(3):289-297.nDickens JR, Bender DA, Bray DE (1996) A critical-angle ultrasonic technique for the inspection of wood parallel-to-grain. Wood Fiber Sci 28(3):380-388.nHan SR, Park CY, Lee IC, Lee JJ (2005) Studies about the effect factors on ultrasonic velocity of domestic red pine. Pp 149-150 in Proc of International Symposium on Wood Science and Technology.nKanda S, Shioya K, Yanagiya Y, Tamura Y, Adachi K (1998) Ultrasonic TOF-CT system for wooden pillars. Pp 743-746 in IEEE Ultrasonics Symposium.nKim KM, Lee JJ (2005a) CT image reconstruction of wood by using ultrasound velocities. I. Effects of reconstruction algorithms and wood characteristics. J Korean Wood Sci Technol 33(5):21-28.nKim KM, Lee JJ (2005b) CT image reconstruction of wood by using ultrasound velocities. II. Determination of the initial model function of the SIRT method. J Korean Wood Sci Technol 33(5):29-37.nKim KM, Lee SJ, Lee JJ (2007) Cross-sectional image reconstruction of wooden member by considering variation of wave velocities. J Korean Wood Sci Technol 35(5):16-23.nSchneider WA Jr., Ranzinger KA, Balch AH, Kruse C (1992) A dynamic programming approach to first arrival travel-time computation in media with arbitrarily distributed velocities. Geophysics 57(1):39-50.nTamura Y, Adachi K, Yanagiya Y, Makino M, Shioya K (1997) Ultrasonic time-of-flight computed tomography for investigation of wooden pillars: Image reconstruction from incomplete time-of-flight profiles. Jpn J Appl Phys 36(5B):3278-3280.nYanagida H, Tamura Y, Kim KM, Lee JJ (2007) Development of ultrasonic time-of-flight computed tomography for hardwood with anisotropic acoustic property. Jpn J Appl Phys 46(8A):5321-5325.nYomikawa Y, Iwase Y, Arita K, Yamada H (1986) Nondestructive inspection of a wooden pole using ultrasonic computed tomography. IEEE Trans Ultrason Ferroelectr Freq Control UFFC-33(4):354-357.n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.