scholarly journals Smoothened Complete Electrode Model

2017 ◽  
Vol 77 (6) ◽  
pp. 2250-2271 ◽  
Author(s):  
Nuutti Hyvönen ◽  
Lauri Mustonen
Keyword(s):  
Complete Electrode Model

scholarly journals The complete electrode model for EIT in a mammography geometry

2007 ◽  
Vol 28 (7) ◽  
pp. S57-S69 ◽  
Author(s):  
Bong Seok Kim ◽  
Gregory Boverman ◽  
Jonathan C Newell ◽  
Gary J Saulnier ◽  
David Isaacson
Keyword(s):  
Complete Electrode Model

JUSTIFICATION OF POINT ELECTRODE MODELS IN ELECTRICAL IMPEDANCE TOMOGRAPHY

2011 ◽  
Vol 21 (06) ◽  
pp. 1395-1413 ◽  
Author(s):  
MARTIN HANKE ◽  
BASTIAN HARRACH ◽  
NUUTTI HYVÖNEN
Keyword(s):  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Analogous Result ◽  
Real Life ◽  
Point Sources ◽  
Reconstruction Problem ◽  
Contact Impedance ◽  
Impedance Tomography ◽  
Point Electrode ◽  
Complete Electrode Model

The most accurate model for real-life electrical impedance tomography is the complete electrode model, which takes into account electrode shapes and (usually unknown) contact impedances at electrode-object interfaces. When the electrodes are small, however, it is tempting to formally replace them by point sources. This simplifies the model considerably and completely eliminates the effect of contact impedance. In this work we rigorously justify such a point electrode model for the important case of having difference measurements ("relative data") as data for the reconstruction problem. We do this by deriving the asymptotic limit of the complete model for vanishing electrode size. This is supplemented by an analogous result for the case that the distance between two adjacent electrodes also tends to zero, thus providing a physical interpretation and justification of the so-called backscattering data introduced by two of the authors.

The simulation of finite ERT electrodes using the complete electrode model

Geophysics ◽  
2011 ◽  
Vol 76 (4) ◽  
pp. F227-F238 ◽  
Author(s):  
Carsten Rücker ◽  
Thomas Günther
Keyword(s):  
Point Source ◽  
Electrode Surface ◽  
Current Source ◽  
Electrical Potential ◽  
Ideal Point ◽  
Point Sources ◽  
Contact Impedance ◽  
Electrode Effect ◽  
Spacing Ratio ◽  
Complete Electrode Model

Direct-current resistivity surveys usually are performed using steel rods of finite extent and grounding resistance. However, in modeling, electrodes are commonly treated as ideal point sources. We present an approach for numerical computation applying the complete electrode model (CEM), which is known from medical imaging. The electrode surface was discretized, and the partial-differential equations were extended by additional relations incorporating a contact impedance and a condition for the current flow through the electrode surface. We verified the modeling of the electrical potential using an analytical solution for a perfectly coupled half-ellipsoid current source. To quantify the influence of a finite electrode, we computed the electrode effect as the ratio between CEM and point-source solution and investigated its dependence on geometry and contact impedance. Surface measurements using rods of typical spatial extent showed electrode effects on the order of the measuring accuracy for an electrode length/spacing ratio lower than 0.2. However, the effects are more significant for closed geometries such as experimental tanks. A comparison with a point approximation for finite electrodes using point-source locations along the electrode axis showed the best agreement, with points at about 60% of the electrode extension. The contact impedance played a minor role for four-point measurements, contributing only a few percent to the electrode effect. In addition to penetrating electrodes, we investigated surface electrodes with galvanic or capacitive coupling, showing electrode effects on the same order as for penetrating electrodes. An inhomogeneous resistivity distribution clearly increased the size of the effects. We also investigate the use of CEM to simulate current injected through steel-cased boreholes. Finally, we applied the approach with buried ring electrodes to calculate effects caused mainly by geometric disturbances from the borehole.

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