Click on image to view larger version.



Fig. 7. Plots showing calibration curves {epsilon}({theta}) obtained with the model by Roth et al. (1990), ({epsilon}s = 2.8, {epsilon}w = 80.36, {epsilon}a = 1.0, {alpha} = 0.52), and from traces measured with twin-rod probes (TRP) and single-rod probes (SRP) of different lengths. Top: SRP300 (300 mm); middle, SRP200 (200 mm); bottom, SRP150 (150 mm). Traces were recorded and analyzed when metallic rods with the same lengths were inserted parallel to the SRPs. The distance between the SRP and the metallic rod were 50 mm (circles), 100 mm (diamonds), and 200 mm (squares); the plus (+) symbols identify the TRP traces.