Role of time and space variability of moisture and density of sand for thermal detection of buried objects: modeling and experiments

摘要

In order to reduce a serious problem connected with the buried mines, various detection technologies are used. The main disadvantage of applying the IRT method is presence of plenty false indications in thermograms. A simple use of IRT equipment with better temperature resolution would not help in distinguishing the mines, since noise comes not from a camera, but from soil surface. Recognizing the role of time and space variability of moisture and density of sand and possibilities to express it quantitatively plays an important role. In our model of thermal properties of the soil the volumetric unit of the soil consists of mineral and organic particles, as well as water and air. All needed parameters can be calculated. Calculations of thermal signatures of the underground objects were made basing on 2D-heat equation for the sinus type heating of the three-layer model of cylindrical geometry and cooling by convection. Measurements were made for field and laboratory stand-ups, using methodologies typical for 'single- shot' measurements as well as analyses of transient processes based on sequence of thermograms. Results of simulations and measurements confirm expectation that high level of 'radiant noises' is caused mainly by differences in the moisture and sand density levels.