8,796 research outputs found
EIT Reconstruction Algorithms: Pitfalls, Challenges and Recent Developments
We review developments, issues and challenges in Electrical Impedance
Tomography (EIT), for the 4th Workshop on Biomedical Applications of EIT,
Manchester 2003. We focus on the necessity for three dimensional data
collection and reconstruction, efficient solution of the forward problem and
present and future reconstruction algorithms. We also suggest common pitfalls
or ``inverse crimes'' to avoid.Comment: A review paper for the 4th Workshop on Biomedical Applications of
EIT, Manchester, UK, 200
Limited Angle Acousto-Electrical Tomography
This paper considers the reconstruction problem in Acousto-Electrical
Tomography, i.e., the problem of estimating a spatially varying conductivity in
a bounded domain from measurements of the internal power densities resulting
from different prescribed boundary conditions. Particular emphasis is placed on
the limited angle scenario, in which the boundary conditions are supported only
on a part of the boundary. The reconstruction problem is formulated as an
optimization problem in a Hilbert space setting and solved using Landweber
iteration. The resulting algorithm is implemented numerically in two spatial
dimensions and tested on simulated data. The results quantify the intuition
that features close to the measurement boundary are stably reconstructed and
features further away are less well reconstructed. Finally, the ill-posedness
of the limited angle problem is quantified numerically using the singular value
decomposition of the corresponding linearized problem.Comment: 23 page
Electrical Resistance Tomography of Conductive Thin Films
The Electrical Resistance Tomography (ERT) technique is applied to the
measurement of sheet conductance maps of both uniform and patterned conductive
thin films. Images of the sheet conductance spatial distribution, and local
conductivity values are obtained. Test samples are tin oxide films on glass
substrates, with electrical contacts on the sample boundary, some samples are
deliberately patterned in order to induce null conductivity zones of known
geometry while others contain higher conductivity inclusions. Four-terminal
resistance measurements among the contacts are performed with a scanning setup.
The ERT reconstruction is performed by a numerical algorithm based on the total
variation regularization and the L-curve method. ERT correctly images the sheet
conductance spatial distribution of the samples. The reconstructed conductance
values are in good quantitative agreement with independent measurements
performed with the van der Pauw and the four-point probe methods.Comment: IEEE Transactions on Instrumentation and Measuremen
Convergence and regularization for monotonicity-based shape reconstruction in electrical impedance tomography
The inverse problem of electrical impedance tomography is severely ill-posed,
meaning that, only limited information about the conductivity can in practice
be recovered from boundary measurements of electric current and voltage.
Recently it was shown that a simple monotonicity property of the related
Neumann-to-Dirichlet map can be used to characterize shapes of inhomogeneities
in a known background conductivity. In this paper we formulate a
monotonicity-based shape reconstruction scheme that applies to approximative
measurement models, and regularizes against noise and modelling error. We
demonstrate that for admissible choices of regularization parameters the
inhomogeneities are detected, and under reasonable assumptions, asymptotically
exactly characterized. Moreover, we rigorously associate this result with the
complete electrode model, and describe how a computationally cheap
monotonicity-based reconstruction algorithm can be implemented. Numerical
reconstructions from both simulated and real-life measurement data are
presented
Reconstruction of a piecewise constant conductivity on a polygonal partition via shape optimization in EIT
In this paper, we develop a shape optimization-based algorithm for the
electrical impedance tomography (EIT) problem of determining a piecewise
constant conductivity on a polygonal partition from boundary measurements. The
key tool is to use a distributed shape derivative of a suitable cost functional
with respect to movements of the partition. Numerical simulations showing the
robustness and accuracy of the method are presented for simulated test cases in
two dimensions
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