FEASIBILITY OF ULTRASONIC TOMOGRAPHY FOR NONDESTRUCTIVE TESTING OF DECAY ON LIVING TREES

Both laboratory and field ultrasonic measurements were carried out to assess the feasibility of ultrasonic tomography for non-invasive testing of living trees. Trees with internal decay were investigated and later cut down. The laboratory measurements, performed on wood disks and specimens, led to the quantitative assessment of the reliability of the tomographic result. Statistical analysis of data allowed considerations to be made on the main aspects connected to the tomographic imaging, such as uncertainty, spatial resolution and anisotropy. The obtained results show that the tomographic image of the ultrasonic velocity distribution is in good agreement with the distribution of the wood decay in the investigated section and the proposed methodology therefore seems to be an improvement on currently used surveying methods.

[1]  H. Berndt,et al.  High-resolution ultrasonic imaging of wood , 1999, Wood Science and Technology.

[2]  A. Alarcón,et al.  FUNDAMENTALS , 2000, Springer Monographs in Mathematics.

[3]  Patricia K. Lebow,et al.  The relationship between stress wave transmission characteristics and the compressive strength of biologically degraded wood , 1997 .

[4]  L. Socco,et al.  ULTRASONIC TOMOGRAPHY FOR WOOD DECAYS DIAGNOSIS. , 2000 .

[5]  A. Furst,et al.  How Much? , 1953, Science.

[6]  Hideki Sailo,et al.  Traveltimes And Raypaths of First Arrival Seismic Waves: Computation Method Based On Huygens’ Principle , 1989 .

[7]  Voichita Bucur,et al.  Dynamic elastic anisotropy and nonlinearity in wood and rock , 1998 .

[8]  S. Ivansson,et al.  Seismic borehole tomography—Theory and computational methods , 1986, Proceedings of the IEEE.

[9]  M. B. Widess.  HOW THIN IS A THIN BED , 1973 .

[10]  Johan Oja.  X-ray measurement of properties of saw logs , 1999 .

[11]  Daryl R. Tweeton.  A tomographic computer program with constraints to improve reconstructions for monitoring in situ mining leachate , 1988 .

[12]  M. Taner,et al.  Complex seismic trace analysis , 1979 .

[13]  Lynne Boddy,et al.  Fungal decomposition of wood , 1988 .

[14]  A. Balch,et al.  A dynamic programming approach to first arrival traveltime computation in media with arbitrarily distributed velocities , 1992 .

[15]  Helge Breloer,et al.  FIELD GUIDE FOR VISUAL TREE ASSESSMENT (VTA) , 1994 .

[16]  R. Lytle,et al.  Computerized geophysical tomography , 1979, Proceedings of the IEEE.

[17]  P. Williamson,et al.  A guide to the limits of resolution imposed by scattering in ray tomography , 1991 .

[18]  E. Wielandt.  On the validity of the ray approximation for interpreting delay times , 1987 .

[19]  Comparison of ART, SIRT, Least-Squares, and SVD Two-Dimensional Tomographic Inversions of Field Data , 1990 .

[20]  S. Rust.  Comparison of three methods for determining the conductive xylem area of Scots pine (Pinus sylvestris) , 1999 .

[21]  D. Jackson.  The use of a priori data to resolve non‐uniqueness in linear inversion , 1979 .

[22]  William Menke,et al.  The resolving power of cross‐borehole tomography , 1984 .

[23]  Voichita Bucur,et al.  Acoustics of Wood , 1995 .

[24]  T. Moser.  Shortest path calculation of seismic rays , 1991 .

[25]  Guust Nolet,et al.  Seismic tomography : with applications in global seismology and exploration geophysics , 1987 .

[26]  G. Kilbertus,et al.  Technique Ultrasonore de Caractérisation du Degré d'Altération des Bois de Hêtre et de Pin Soumis à l'Attaque de Différents Champignons , 1991 .

[27]  A. Käärik.  5 – Decomposition of Wood , 1974 .

[28]  P. Gilbert.  Iterative methods for the three-dimensional reconstruction of an object from projections. , 1972, Journal of theoretical biology.

[29]  Y. Tomikawa,et al.  Nondestructive Inspection of a Wooden Pole Using Ultrasonic Computed Tomography , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[30]  V. Bucur,et al.  Elastic constants for wood by an ultrasonic method , 1984, Wood Science and Technology.

[31]  Lynne Boddy,et al.  Fungal decomposition of wood. Its biology and ecology. , 1988 .

[32]  M. Worthington,et al.  An introduction to geophysical tomography , 1984 .