Wood grain angle estimation in logs with microwave modelling

Sjödén, Therese; Nordebo, Sven; Nilsson, Börje

doi:10.1063/1.2205811

Cited by 2 publications

(3 citation statements)

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“…First and are determined by comparisons with measurements in (19) of and in the same polarization as the source, with the result and . Then the solution that minimizes the quadratic error in (20) is (21) For the general solution of (19) and (20) as well as (21), the error can be reduced by taking mean values over time. The error analysis is expanded in Section VII.…”

Section: Inverse Scatteringmentioning

confidence: 99%

“…With the super index denoting a measured quantity, we get (19) and (20) The over determined system (19) and (20), used to find the pitch and the surface impedance parameters and for the cylinder, constitutes the general formulation of the inverse scattering problem. We will also show a simplified inverse scattering theory by giving a simple expression for .…”

Section: Inverse Scatteringmentioning

confidence: 99%

“…The dielectric properties were measured simultaneously making the method insensitive to variations in temperature and humidity. The errors for this method were analyzed with [17] and without [19] information of the dielectric properties with the conclusion that there exists a frequency interval for determining the pitch with sufficient accuracy. That it is possible to determine the twist for a frozen material has been demonstrated experimentally [16] for the planar case.…”

Section: Introductionmentioning

confidence: 99%

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Estimation of Twist in Uniaxial Cylinders With Inverse Electromagnetic Scattering

Nilsson

Nordebo

Sojden

2009

IEEE Trans. Antennas Propagat.

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For the purpose of determining the twist of a homogeneous, locally reacting, uniaxial cylinder, an inverse microwave scattering theory is presented. Remote measurements of the spiral grain of trees and logs are the prime application. Based on practical considerations, it is assumed that the transmitting and receiving antennas are collocated, requiring a three-dimensional modelling. A general theory is first developed, followed by an asymptotic analysis assuming that the distance from the antennas to the cylinder is many wavelengths and many cylinder radii. In this way, a substantial reduction of the numerical complexity, to the level of the two-dimensional case, is achieved. The error of the determined twist angle as function of inherent parameters of the problem using a Cramér-Rao analysis is given. The results from numerical simulations show that this error is low enough for determining the grain angle. Presented parameter studies of the error can be used for minimizing the errors in a measurement set up, of particular interest for non-sophisticated instruments and non-ideal laboratory conditions, by selecting optimum parameters such as frequency and antenna gain. Finally, it is stated that the model has a great potential for developing efficient algorithms for measuring the twist angle.

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Section: Inverse Scatteringmentioning

confidence: 99%

Section: Inverse Scatteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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