Study On Image Fusion And Image Reconstruction Algorithm For Electrical Capacitance Tomography System

Electrical capacitance tomography (ECT) technique is a kind of processtomography technique that rapid develops in recent years. Because ofcapacitance sensitivity principle which this technique bases on, there are severaladvantages such as low cost, fast response, non-invasion, wide application range,etc, which make it become the hotspot in the research of flow tomography. Thistechnique has great potential for development and extensive application inindustry. Up till the present moment, the performance of ECT is far from thedemands in their practical application, therefore, it needs further exploration andresearch.Image reconstruction is an import link in the electrical capacitancetomography system. The main parameters of the multiphase flow calculationcontain phase holdup, flow feature, flow meter, speed, density, etc. Themeasurement and judgment of those parameters are difficult and fuzzy. Toestablish the nonlinear mapping relationship between capacitance values and thegray-level of images’ pixel is the gist of image reconstruction, then therelationship should be achieved by some image reconstruction algorithm andfinally the distribution of the medium will be Inversed from the capacitancevalues. But at this stage, influenced by many factors, there is no way toreconstruct an image of the flow in an accurate form. During the reconstruction,there are many different algorithms to use, therefore different results exist. Thereason for this has to do with the sensibility from different algorithm for differentflow, this makes us consider the technique of image fusion that could make theresult precise and the main contents are as follows:To begin with, in the background of this subject, the application and significance of the measurement of multiphase flow and analyzed the majorparameters have been introduced, we also talk about the Future Trends of thistechnique.The next, the System configuration and the operating principle of ECT havebeen introduced in this paper, by building mathematics model, we can analyzethe principle of Image reconstruction that based on the distribution of sensitivityfield.Once again, this thesis surveys the basic principle and methods of imagefusion and describes how to use this method in the ECT system in order toimprove the accuracy of the images.Finally, we divide the images into tow parts, low frequency sub-image andhigh frequency sub-image. Different parts have different fusion method,especially the high frequency sub-image, we used area-energy method based onwindow.By knowing how ECT system and image fusion work, we can combine theadvantages of both in order to get a better image.