Vibration-Induced Conductivity Fluctuation (VICOF) Testing of Soils
  In this Letter, we propose and experimentally demonstrate a simple method to provide additional in-formation by conductivity measurements of soils. The AC electrical conductance of the soil is measured while it is exposed to a periodic vibration. The vibration-induced density fluctuation implies a corresponding conductivity fluctuation that can be seen as combination frequency components, the sum and the difference of the mean AC frequency and the double of vibration frequency, in the current response. The method is demonstrated by measurements on clayey and sandy soils. 
Laszlo B. Kish, Cristine L.S. Morgan, Andrea Sz. Kishne