given in Section \[sec:CompDetails\]. Section \[sec:results\] presents absolute and time-difference EIT reconstructions using experimental data from three EIT systems. Results are compared for various errors in electrode placement and domain shape modeling [[and a]{}]{} discussion of the results [[included. Conclusions are]{}]{} stated in Section \[sec:conclusions\].

Methods {#sec:methods}
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Letting $\Omega\subset{{\mathbb R}}^2$ denote a simply connected domain with Lipschitz boundary, the electric potential inside $u$ inside $\Omega$ can be modeled by a generalized Laplace equation, also called the [*admittivity equation*]{} $$\label{eq:admitt}
\nabla\cdot\gamma(z)\nabla u(z) = 0,\quad z\in\Omega\subset{{\mathbb R}}^2,$$ where $\gamma(z)=\sigma(z)+i\omega\epsilon(z)$ denotes the admittivity with conductivity $\sigma$, permittivity $\epsilon$, and frequency $\omega$. The EIT problem is then to recover the coefficient $\gamma(z)$ for all $z\in\Omega$ from electrical measurements taken on the surface [[$\operatorname{\partial\Omega}$]{}]{}. These measurements take the form of Neumann-to-Dirichlet (ND) data $(g,f)$ where $g$ are the applied currents and $f$ the corresponding voltages: $\mathcal{R}_\gamma g=f$. Knowledge of the ND map allows one to predict the resulting boundary voltages for any applied current. For full boundary data, the Dirichlet-to-Neumann (DN) map is the inverse of the ND map: $\Lambda_\gamma = \left(\mathcal{R}_\gamma\right)^{-1}$.

D-bar methods are based on using a nonlinear Fourier transform of the DN data tailored to the EIT problem. The admittivity is 