Depth estimation of cavities from microgravity data using a new approach: the local linear model tree (LOLIMOT)

Abstract

In this paper an attempt is made to estimate depth and shape parameters of subsurface cavities from microgravity data through a new soft computing approach: the locally linear model tree, known as the LOLIMOT algorithm. This method is based on locally linear neuro‐fuzzy modelling, which has recently played a successful role in various applications over non‐linear system identification. A multiple‐LOLIMOT neuro‐fuzzy model was trained separately for each of the three most common shapes of subsurface cavities: sphere, vertical cylinder and horizontal cylinder. The method was then tested for each of the cavity shapes with synthetic data. The model's suitability for application to real cases was analysed by adding random Gaussian noise to the data to simulate several levels of uncertainty and the results of LOLIMOT were compared to both multi‐layer perceptron neural network and least‐squares minimization methods. The results showed that the LOLIMOT algorithm is more robust to noise and is also more precise than either the multi‐layer perceptron or least‐squares minimization method. Furthermore, the method was tested with microgravity data over a selected site located in a major container terminal at Freeport, Grand Bahamas, to estimate cavity depth and was compared to the results achieved by least‐squares minimization and multi‐layer perceptron methods. The proposed method can estimate cavity parameters more accurately than the least‐squares minimization and multi‐layer perceptron methods.

Removing Regional Trends in Microgravity in Complex Environments: Testing on 3D Model and Field Investigations in the Eastern Dead Sea Coast (Jordan)

“…Kaufmann et al [43] successfully employed microgravity to identify subsurface voids in the Unicorn cave in the Harz Mountains (Germany). Hajian et al [33] applied locally linear neurofuzzy microgravity modeling to the three most common shapes of subsurface cavities: sphere, vertical cylinder, and horizontal cylinder. The authors showed that their method can estimate cavity parameters more accurately than least-squares minimization or multilayer perceptron methods.…”

Semiautomatic interpretation of microgravity data from subsurface cavities using curvature gradient tensor matrix

“…The new inversion methods (Fedi and Rapolla ; Li and Oldenburg ) require a large amount of computer memory and computation time. Some of the new methods (Elawadi et al ; Hajian et al ) can only be used to interpret profile data. Some other new methods (Abdelrahman et al ; Salem et al ) can be used to determine the depth and shape factor of the causative sources, but they are insufficient to delineate the edges of cavities.…”