R. Wajman

Four-dimensional electrical capacitance tomography imaging using experimental data

Electrical capacitance tomography (ECT) is a relatively mature non-invasive imaging technique that attempts to map dielectric permittivity of materials. ECT has become a promising monitoring technique in industrial process tomography especially in fast flow visualization. One of the most challenging tasks in further development of ECT for real applications are the computational aspects of the ECT imaging. Recently, 3D ECT has gained interest because of its potential to generate volumetric images. Computation time of image reconstruction in 3D ECT makes it more difficult for real time applications. In this paper we present a robust and computationally efficient 4D image reconstruction algorithm applied to real ECT data. The method takes advantage of the temporal correlation between 3D ECT frames to reconstruct movies of dielectric maps. Image reconstruction results are presented for the proposed algorithms for experimental ECT data of a rapidly moving object.

Three-Dimensional Nonlinear Inversion of Electrical Capacitance Tomography Data Using a Complete Sensor Model

Electrical Capacitance Tomography (ECT) is a non- invasive and non-destructive imaging technique that uses electrical capacitance measurements at the periphery of an object to generate map of dielectric permittivity of the object. This visualization method is a relatively mature industrial process tomography technique, especially in 2D imaging mode. Volumetric ECT is a new method that poses major computational challenges in image reconstruction and new challenges in sensor design. This paper shows a nonlinear image reconstruction method for 3D ECT based on a validated forward model. The method is based on the flnite element approximation for the complete sensor model and the solution of the inverse problem with nonlinear iterative reconstruction. The nonlinear algorithm has been tested against some complicated experimental test cases, and it has been demonstrated that by using an improved forward model and nonlinear inversion method, very complex shaped samples can be reconstructed. The reconstruction of very complex geometry with objects in the shape of letters H, A, L and T is extremely promising for the applications of 3D ECT.

Metrological evaluation of a 3D electrical capacitance tomography measurement system for two-phase flow fraction determination

The industrial diagnostic and monitoring systems still require new methods offering new possibilities of non-invasive observation and analysis of the two-phase gas–liquid mixture flows. This paper demonstrates a new measurement system dedicated for non-invasive void fraction calculation and flow structure identification in vertical and horizontal pipelines. The study of the metrological validation of the designed three-dimensional capacitance tomography measurement system is discussed here. This research includes the 3D ECT sensor structure optimization process, the metrological evaluation of the image reconstruction accuracy and the developed liquid void fraction calculation method efficiency, in comparison with other common techniques. As a result of the performed analysis the advantages of the designed 3D ECT measurement system for non-invasive real-time dynamic flow process identification were discussed.

Tunnel-based method of sensitivity matrix calculation for 3D-ECT imaging

Purpose – The purpose of this paper is to introduce a significant modification of the sensitivity maps calculation process using electric field distribution analysis. A sensitivity matrix is typically a crucial part of a deterministic image reconstruction process in a three-dimensional capacitance tomography (3D ECT) and strictly decides about a final image quality. Commonly used sensitivity matrix computation methods mostly provide acceptable results and additionally allow to perform a recalculation of sensitivity maps according to the changing permittivity distribution. Design/methodology/approach – The new “tunnel-based” algorithm is proposed which traces the surfaces constructed along the electric field lines. The new solution is developed and tested using experimental data. Findings – To fully validate the new technique both linear and non-linear image reconstruction processes were performed and the criteria of image error estimation were discussed. This paper discusses some preliminary results of th...

THE FUZZY SYSTEM FOR RECOGNITION AND CONTROL OF THE TWO PHASE GAS-LIQUID FLOWS

In this article the fuzzy system for the two phase gas-liquid flows recognition based on the 3D tomography data and the research facility context information is described., The system is also specialized to control the research facility in basis of the fuzzy algorithms and generated diagnostics signals.

MULTI PHASE FLOW MEASUREMENTS WITH THE APPLICATION OF ECT/ERT DECART MULTIMODALITY TOMOGRAPH

The multi-phase flow measurements are very important tasks in many areas of industrial processes applications. One of them is undersea exploration of oil in the petroleum industry. The submitted paper presents application of DECART tomograph designed and built in Lodz University of Technology together with combined measurements of signals acquired from gamma ray measurement system. Use of all measuring modalities allowed for performing measurements of a flow composed of sea water, oil and gas. The paper presents theoretical principles applied to design multimodality tomograph and results of experiments performed in the University of Bergen. Measurement confirmed that multi-modality approach allows giving fast and reliable on-line results of measurements of composition of multi-phase flow. Applied algorithms allowed to speed up on-line measurements and presenting results in a form required in industrial applications. The derived conclusions can be used as guidelines for preparation of industrial applicable construction of tomograph.