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@PHDTHESIS{Verweerd:58944,
      author       = {Verweerd, Arre Job},
      title        = {{P}erformance {A}nalysis and {C}haracterisation of a new
                      {M}agneto-{E}lectrical {M}easurement {S}ystem for
                      {E}lectrical {C}onductivity {I}maging},
      volume       = {75},
      school       = {Universität Bonn},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-58944},
      isbn         = {978-3-89336-495-4},
      series       = {Schriften des Forschungszentrums Jülich. Reihe Umwelt /
                      Environment},
      pages        = {108 S.},
      year         = {2007},
      note         = {Record converted from VDB: 12.11.2012; Universität Bonn,
                      Diss., 2007},
      abstract     = {An often used proxy in hydrogeology is the electrical
                      condutctivity distributioni to study flow and transport of
                      groundwater in soil. In order to map the electrical
                      conductivity distribution of soil columns (length 0.5 m and
                      0.1 m radius), traditionally ERT (Electrical Resistivity
                      Tomography) is used. In this thesis the ERT measurements
                      will be complimented by magnetometric resistivity (MMR)
                      mearurements. Due to a low frequency current injection (25
                      Hz) a current distribution is generated in the soil column
                      of which the electrical potential is measured at several
                      electrodes. This current has an associated magnetic field,
                      also depending on the internal electrical conductivity
                      distribution, this resulting magnetic field is measured in
                      the MMR method. The magneto-electrical resistivity imaging
                      technique (MERIT) combines the measurement of both electric
                      and magnetic parameters. In this thesis the development of a
                      small laboratory scale system will be described. The
                      electrical potentials are measured by small stainless steel
                      screws inserted into the plexiglass mantle of the soil
                      column, the magnetic fields are measured with especially
                      designed sensor modules. The three component magnetic field
                      modules are composed of AMR sensors, and are located on a
                      vertical moving scanning torus. The magnetic field
                      measurement system is designed to operate under
                      ’typical’ laboratory noise conditions. The development
                      of this new measurement system also includes optimization of
                      the sensor positions and current injection geometries. The
                      technique of singular value decomposition is applied to the
                      Jacobian (or sensitivity matrix) of a combined ERT and MMR
                      dataset in order to obtain information on the behaviour of
                      the system in the so-called model space as well as its data
                      space. This information can be used to obtain a quantitative
                      measure of the optimum measurement configuration and the
                      optimum resolution of the MERIT system, depending on the
                      target of the survey. Finally a 2D quasi-Newton inversion
                      algorithm with Broyden type Jacobian updating is used in
                      order to image the electrical conductivity distribution of
                      the soil column.},
      cin          = {ICG-4},
      ddc          = {333.7},
      cid          = {I:(DE-Juel1)VDB793},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/58944},
}