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INHALTE

Geomagnetic prospection system for ground surveys

Project description

In this project, a new method to analyse the ground for building measures is developed. It bases on geomagnetic prospection, whereas the gradient of the magnetic field of the earth is measured and mapped over the area of interest. The designed measurement system utilises the currently most sensitive type of gradiometer sensors: Superconducting Quantum Interference Devices (SQUIDs). Due to their extremely high sensitivity in comparison to conventional gradiometers, local changes of the magnetic field of the earth that arise by different susceptibilities of the underground can be resolved with high precision. Such changes are caused by the geological properties and condition of the underground, but also by cavities or buried objects. By using two vertically arranged gradiometers, depths information of the objects that produce the anomalies in the magnetic field are obtained. The measurement system is conjointly developed at the IPHT Jena and the Supracon AG Jena.
The result of the magnetic field mapping, which is an assignment of the measured gradients to the prospective building ground with a precision of a few centimetres, has to be processed further to extract application relevant data. The required software methods are developed by the Friedrich Schiller University Jena and the University of Technology Ilmenau. Thereby, two different approaches are pursued: a pattern recognition approach of artificial neural networks and source localisation methods that use the measured magnetic signals. Finally, JenControl realises an efficient software implementation of the developed algorithms and a user interface for handling large volumes of data

Image 1: Mapping of the measured magnetic field from a test area in Münchenroda near Jena

Image 2: Results of the source reconstruction in a depth of Z=-1m for the
measurement data shown in Fig. 1. A minimum-norm-estimation approach is used.
The results indicate 5 regions containing buried ferromagnetic objects.

Project partner

  • Supracon AG, Jena
  • JenControl GmbH, Jena
  • Institute of Photonic Technology (IPHT), Jena
  • Friedrich-Schiller-University Jena, Institute of Materials Science and Technology

Publications & patents

  • R. Eichardt and J. Haueisen. Influence of sensor variations on the condition of the magnetostatic linear inverse problem. IEEE Transactions on Magnetics, 46(8): 3449–3453, 2010. doi:10.1109/TMAG.2010.2046149.
  • R. Eichardt, D. Baumgarten, L. Di Rienzo, S. Linzen, V. Schultze, and J. Haueisen. Localisation of buried ferromagnetic objects based on minimum-norm-estimations – a simulation study. COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 28(5):1327–1337, 2009. doi:10.1108/03321640910969566.
  • R. Eichardt, C. H. Igney, J. Kahlert, M. Hamsch, M. Vauhkonen, and J. Haueisen. Sensitivity comparisons of cylindrical and hemi-spherical coil setups for magnetic induction tomography. In O. Dössel and W. C. Schlegel, editors, Proceedings of the World Congress on Medical Physics and Biomedical Engineering, 7 – 12 September 2009, Munich, Germany, volume 25/IV of IFMBE Proceedings, pages 269–272, 2009. doi:10.1007/978-3-642-03882-2_71.
  • R. Eichardt, J. Haueisen, T. R. Knoesche, and E. G. Schukat-Talamazzini. Reconstruction of multiple neuromagnetic sources using augmented evolution strategies – a comparative study. IEEE Transactions on Biomedical Engineering, 55(2, Part 1):703–712, 2008. doi:10.1109/TBME.2007.912656.
  • S. Lau, R. Eichardt, L. Di Rienzo, and J. Haueisen. Tabu search optimization of magnetic sensor systems for magnetocardiography. IEEE Transactions on Magnetics, 44(6): 1442–1445, 2008. doi:10.1109/TMAG.2007.915911.