Limestone has been a widely used building material for many years. Its degradation process has been strongly linked to its water content, to which the radar waves are sensitive. In this paper, the closed-form, near-field full-wave radar model of Lambot et al. is utilized for monitoring water ingress in limestone. This model is based on planar layered media Green's functions combined with an intrinsic representation of the antenna through global reflection and transmission functions. The Jonscher model is used to describe the frequency dependence of the limestone electromagnetic properties. Then, an inversion method based on a genetic algorithm is developed and optimized. The method is numerically validated by simulating electromagnetic wave propagation in medias, using a three-dimensional finite element software, namely high-frequency electromagnetic field simulation. Finally, the method is experimentally validated, with a stepped-frequency radar system and an ultrawide band antenna, during an imbibition process of a limestone slab. Results are compared to gammadensimetry measurements, a nuclear and semidestructive approach, performed as the reference. Analyses of the results show that the average relative difference between the estimated and the reference water front is 2.5%, thereby demonstrating the performance of the proposed nondestructive method.

In the field of geophysics and civil engineering applications, ground penetrating radar (GPR) technology has become one of the emerging non-destructive testing (NDT) methods thanks to its ability to perform tests without damaging structures. However, NDT applications, such as concrete rebar assessments, utility network surveys or the precise localization of embedded cylindrical pipes still remain challenging. The inversion of geometric parameters, such as depth and radius of embedded cylindrical pipes, as well as the dielectric parameters of its surrounding material, is of great importance for preventive measures and quality control. Furthermore, the precise localization is mandatory for critical underground utility networks, such as gas, power and water lines. In this context, innovative signal processing techniques associated with GPR are capable of performing physical and geometric characterization tasks. This paper evaluates the performance of a supervised machine learning and ray-based methods on GPR data. Support vector machines (SVM) classification, support vector machine regression (SVR) and ray-based methods are all used to correlate information about the radius and depth of embedded pipes with the velocity of stratified media in various numerical configurations. The approach is based on the hyperbola trace emerging in a set of B-scans, given that the shape of the hyperbola varies greatly with pipe depth and radius as well as with velocity of the medium. According to the ray-based method, an inversion of the wave velocity and pipe radius is performed by applying an appropriate nonlinear least mean squares inversion technique. Feature selection within machine learning models is also implemented on the information chosen from observed hyperbola travel times. Simulated data are obtained by means of the finite-difference time-domain (FDTD) method with the 2D numerical tool GprMax. The study is carried out on mono-static, ground-coupled GPR datasets. The preliminary study showed that the proposed machine learning methods outperforms the ray-based method for estimating radius, depth and velocity. SVR, for instance, calculates depth and radius values with mean absolute relative errors of 0.39% and 6.3%, respectively, with regard to the ground truth. A parametric comparison of the aforementioned methodologies is also included in the performance analysis in terms of relative error.

In this paper, principal-singular-vector utilization for modal analysis (PUMA) was adapted to perform time delay estimation on ground-penetrating radar (GPR) data by taking into account the shape of the transmitted GPR signal. The super-resolution capability of PUMA was used to separate overlapping backscattered echoes from a layered pavement structure with some embedded debondings. The well-known root-MUSIC algorithm was selected as a benchmark for performance assessment. The simulation results showed that the proposed PUMA performs very well, especially in the case where the sources are totally coherent, and it requires much less computational time than the root-MUSIC algorithm.

A robust blind deconvolution algorithm is proposed to cancel the sensor averaging effect caused by its wide detection area. The purpose herein is to retrieve features of the real signal that have been distorted by the averaging effect. The algorithm is applied to the case of an inductive loop detector. To perform the proposed algorithm, speed estimation is required. Vehicle reidentification rate from both raw signals and estimated real signals is compared. The sensor transfer function is calculated once from a learning phase; the estimated real signal is then computed in real time for the reidentification of each vehicle.

This paper focuses on the development and validation of an innovative method for estimating the degree of saturation in limestone. A protocol is designed to control, homogenize and validate such an estimation. The complex dielectric permittivity is acquired from the coaxial electromagnetic transition line on a limited frequency bandwidth. Calibration curves connecting the dielectric permittivity and the degree of saturation are obtained. The use of variants of Jonscher’s model makes it possible to overcome the frequency dependence and propose a relationship between Jonscher model parameters and the degree of saturation. A supervised learning method (v-SVR) has been successfully introduced to estimate the degree of saturation from these parameters. The results have been experimentally validated on a wide range of limestone samples.

This letter presents a vehicle detection state machine for magnetometer sensors. The state machine designed by Chinrungrueng and Kaewkamnerd for a single lane is extended to n motorway lanes with multiple lane changes. The proposed method has good performance in terms of the detection rate and the false detections, which are mainly due to the interference from a vehicle in an adjacent lane and lane changing. The state machine is evaluated on a real motorway and compared with industrial sensors.