GPR imaging techniques for non-destructive inspection of concrete structures

open4noVol. 21, EGU2019-8897openRandazzo, Andrea; Fedeli, Alessandro; Pastorino, Matteo; Pajewski, LaraRandazzo, Andrea; Fedeli, Alessandro; Pastorino, Matteo; Pajewski, Lar

Lunar Gravitational-Wave Antenna

Monitoring of vibrational eigenmodes of an elastic body excited by gravitational waves was one of the first concepts proposed for the detection of gravitational waves. At laboratory scale, these experiments became known as resonant-bar detectors first developed by Joseph Weber in the 1960s. Due to the dimensions of these bars, the targeted signal frequencies were in the kHz range. Weber also pointed out that monitoring of vibrations of Earth or Moon could reveal gravitational waves in the mHz band. His Lunar Surface Gravimeter experiment deployed on the Moon by the Apollo 17 crew had a technical failure rendering the data useless. In this article, we revisit the idea and propose a Lunar Gravitational-Wave Antenna (LGWA). We find that LGWA could become an important partner observatory for joint observations with the space-borne, laser-interferometric detector LISA, and at the same time contribute an independent science case due to LGWA's unique features. Technical challenges need to be overcome for the deployment of the experiment, and development of inertial vibration sensor technology lays out a future path for this exciting detector concept.Comment: 29 pages, 17 figure

Improved quadrature formulas for boundary integral equations with conducting or dielectric edge singularities

In this paper we derive new two-dimensional (2-D) quadrature formulas for the discretization of boundary integral equations in the presence of conducting or dielectric edges. The proposed formulas allow us to exactly integrate polynomials of degree less than or equal to five, multiplied by an algebraic singular factor that diverges along one side of the triangular integration domain. This is the kind of singularity that occurs when physical edges are present in both conducting and dielectric bodies. Numerical tests are performed on the presented formulas, in order to validate the achieved improvement in accuracy, and examples are given of their application to the determination of radar cross-section of 3-D metallic objects

System for positioning and tracking of GPR based on inertial and GPS data integration

All applications that use GPR in remote mode need to combine to the radar an accurate positioning system. Such system allows to solve errors in the localisation of buried objects, which are generated by the measurement conditions, i.e.: by the slope of soil, in the case of a ground-coupled radar, and by the airplane attitude, in the case of a GPR mounted on aerial vehicle. This paper presents the implementation of a low-cost system for determining positioning, tracking and trim data of GPR. This system integrates data of a Global Positioning System (GPS) with those of an Inertial Measurement Unit (IMU)

Tomographic reconstruction of structures using a novel GPR system

The ever growing range of applications of ground penetrating radar (GPR) motivates the need of developing efficient measurement systems combined with effective data processing methods. On the one hand, advanced GPR measurement systems require to accurately model the physical effects occurring between the antenna structure and the medium. On the other hand, the GPR device should provide a reliable reconstruction of the properties of the targets under an inspection to a common user