A Comparison Between Electrical Capacitance Tomography and Displacement-Current Phase Tomography

We compare electrical capacitance tomography (ECT) and displacement-current phase tomography (DCPT) results for non-invasive imaging of lossy media. ECT is based on mutual capacitance measurements between electrode pairs surrounding the region of interest (RoI), whereas DCPT is a relatively less mature sensing modality that utilizes the phase information inherent in the displacement current measured by such electrode pairs excited by time-harmonic voltages (in the electroquasistatic regime). DCPT and ECT can be implemented using basically the same hardware components and used alongside to provide complementary information for imaging purposes or separately to reconstruct the spatial distribution of the loss tangent or the permittivity within the RoI, respectively. We show that the (nonlinear) relationship between the measured phase in DCPT and the conductivity distribution in the RoI has a more extended linear range than the nonlinear relationship between the measured capacitances in ECT and the permittivity distribution in the RoI. Of note, DCPT does not require electrical contact with the RoI in contrast to electrical impedance tomography. To illustrate the potential of DCPT, we evaluate its performance using both numerical examples and experiment results.

[1]  Wuqiang Yang,et al.  Electrical capacitance tomography for gas–solids flow measurement for circulating fluidized beds , 2005 .

[2]  Wuqiang Yang,et al.  Design of electrical capacitance tomography sensors , 2010 .

[3]  Lihui Peng,et al.  Image reconstruction algorithms for electrical capacitance tomography , 2003 .

[4]  Wuqiang Yang,et al.  Measurement of fluidised bed dryer by different frequency and different normalisation methods with electrical capacitance tomography , 2010 .

[5]  David Isaacson,et al.  Electrical Impedance Tomography , 1999, SIAM Rev..

[6]  Tomasz Dyakowski,et al.  Application of electrical capacitance tomography for measurement of gas-solids flow characteristics in a pneumatic conveying system , 2001 .

[7]  M. S. Beck,et al.  Capacitance-based tomographic flow imaging system , 1988 .

[8]  A. Liao,et al.  Application of ECT and relative change ratio of capacitances in probing anomalous objects in water , 2015 .

[9]  J. L. Davidson,et al.  Three-dimensional electrical impedance tomography applied to a metal-walled filtration test platform , 2004 .

[10]  F. Teixeira,et al.  Sensitivity matrix calculation for fast 3-D electrical capacitance tomography (ECT) of flow systems , 2004, IEEE Transactions on Magnetics.

[11]  R. C. Waterfall,et al.  Calibration of capacitance tomography systems for liquid-liquid dispersions , 1998 .

[12]  Maurice Beck,et al.  Design of capacitance electrodes for concentration measurement of two-phase flow , 1990 .

[13]  Joel T. Johnson,et al.  Radiowave Propagation: Physics and Applications , 2010 .

[14]  F. Teixeira,et al.  A nonlinear image reconstruction technique for ECT using a combined neural network approach , 2006 .

[15]  Richard A Williams,et al.  Simulation of the performance of electrical capacitance tomography for measurement of dense phase pneumatic conveying , 1997 .

[16]  Dominik Sankowski,et al.  Electrostatic field simulations in the analysis and design of electrical capacitance tomography sensors , 2010 .

[17]  Wuqiang Yang,et al.  New AC-based capacitance tomography system , 1999 .

[18]  Wuqiang Yang,et al.  Design of Impedance Measuring Circuits Based on Phase-Sensitive Demodulation Technique , 2011, IEEE Transactions on Instrumentation and Measurement.

[19]  Dieter Mewes,et al.  Investigation of the Two-Phase Countercurrent Flow In Structured Packings Using Capacitance Tomography , 1999 .

[20]  A V Korjenevsky,et al.  Electric field tomography for contactless imaging of resistivity in biomedical applications , 2004, Physiological measurement.

[21]  Hannes Wegleiter,et al.  Development of a displacement current-based sensor for electrical capacitance tomography applications , 2008 .

[22]  Wuqiang Yang,et al.  Optimization of an iterative image reconstruction algorithm for electrical capacitance tomography , 1999 .

[23]  Brian Scarlett,et al.  Monitoring Particle Flows by Displacement Current Sensing , 1999 .

[24]  Fernando L. Teixeira,et al.  Adaptive Electrical Capacitance Volume Tomography , 2014, IEEE Sensors Journal.

[25]  Liang-Shih Fan,et al.  Electrical capacitance tomography , 2015 .

[26]  Xiaodong Jia,et al.  Analysis and flow regime identification of bubble column dynamics , 1999 .

[27]  Liang-Shih Fan,et al.  A Multimodal Tomography System Based on ECT Sensors , 2007, IEEE Sensors Journal.

[28]  Fernando L. Teixeira,et al.  Sensitivity map computation in adaptive electrical capacitance volume tomography with multielectrode excitations , 2015 .

[29]  Artur J. Jaworski,et al.  The design of an electrical capacitance tomography sensor for use with media of high dielectric permittivity , 2000 .

[30]  Fernando L. Teixeira,et al.  Dual imaging modality of granular flow based on ECT sensors , 2008 .

[31]  Brian S. Hoyle,et al.  Electrical capacitance tomography for flow imaging: system model for development of image reconstruction algorithms and design of primary sensors , 1992 .

[32]  Trevor A. York,et al.  Status of electrical tomography in industrial applications , 2001, SPIE Optics East.

[33]  Hermann A. Haus,et al.  Electromagnetic Fields And Energy , 1989 .

[34]  S. Mylvaganam,et al.  Electrical Capacitance Tomography—Sensor Models, Design, Simulations, and Experimental Verification , 2006, IEEE Sensors Journal.

[35]  Manuchehr Soleimani,et al.  Simultaneous reconstruction of permittivity and conductivity using multi-frequency admittance measurement in electrical capacitance tomography , 2016 .

[36]  Radosław Wajman,et al.  Electrical capacitance tomography: image reconstruction along electrical field lines , 2001 .

[37]  Kwang Youn Kim,et al.  Modified iterative Landweber method in electrical capacitance tomography , 2006 .

[38]  A V Korjenevsky,et al.  Phase measurement for electric field tomography. , 2008, Physiological measurement.