Measurement of moisture gradient in wood by Electrode Scanning Moisture Analysis ESMA
Sobue, N.
2000 Wood NDT-2000, 12th International Symposium on Nondestructive Testing of Wood, University of Western Hungary, Sopron, 13-15 September
Sobue, N., (2000), "Measurement of moisture gradient in wood by Electrode Scanning Moisture Analysis ESMA", Wood NDT-2000, 12th International Symposium on Nondestructive Testing of Wood, University of Western Hungary, Sopron, 13-15 September.
Abstract:
A new principle of dielectric moisture meter measuring moisture content gradient in wood was proposed. This new type device is named as Electrode Scanning Moisture Analyzer (ESMA) because moisture signal is detected by measuring capacitance change during electrode scanning.
Capacitance decreased logarithmically with increase of electrode distance, and patterns of capacitance-electrode distance curve reflected moisture content distribution in wood.
Moisture distribution was denoted by a first kind Fredholm type integral equation by using capacitance change due to change of electrode distance and a kerner function, which was given by capacitance sensibility per unit moisture content.
The integral equation was solved by rewriting it to discreet algebraic equation. The solution altered very much and showed "ill-posed" problem. However, smoothing of data using least square method showed good reproduce of moisture distribution.
These results showed that the principle of the electrode scanning moisture analyzer is effective to estimate moisture content gradient in wood.