Dominik Sankowski

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.

The 'best-correlated pixels' method for solid mass flow measurements using electrical capacitance tomography

A novel method of calculating a solid velocity field based on a twin-plane electrical capacitance system is presented. This method introduces the concept of the best-correlated pair of pixels instead of the classical assumption that a flow pattern between two sensor planes is frozen. Preliminary results and future applications of the proposed method are discussed.

Automatic investigation of surface phenomena in high temperature solid and liquid contacts

In the paper newly developed system for automatic measurements of surface properties is presented. The results obtained with the device described in this paper are far more accurate than those obtained by means of the currently applied non automatic methods based on the operators evaluation.

Computer vision system for high temperature measurements of surface properties

Recently, computer vision systems have become very popular. They are of great importance in almost every field of science, engineering and industry. Present-day vision systems allow to obtain information that is normally not distinguishable by humans. It is possible due to use of appropriate digital image processing and analysis algorithms. The paper explains importance of proper image processing algorithms selection for computer vision applications. Particular industrial image quantitative analysis systems are considered. Computerized system for high-temperature measurements of surface properties is used as an example. The system is capable of measuring wetting angle and surface tension of metals, alloys and other materials (e.g. glass) in temperatures up to 1,800°C. A brief description of the system is given. Particularly, attention is paid to preprocessing algorithms. They consider not only typical factors that usually accompany digital images founded analysis but also specificity of images obtained during the measurement process as well. Correction of factors arising from CCD camera electronic components and reduction of aura (glow that appears around specimen in high temperatures) affects with high quality image segmentation. In consequence the accuracy of surface parameters determination is increased.

Computerized device with CCD camera for measurement of surface tension and wetting angle in solid-liquid systems

In this paper, a computerized device with the CCD camera for the automatic determination of important surface properties of liquid and solid in contact is described. This device is based on image processing algorithms. The system is capable of measuring the surface tension (surface energy) of liquid and the wettability of a solid surface in the wide range of temperatures, up to 1800/spl deg/C. The results obtained with this device are far more accurate than those obtained by means of the currently applied, extremely time consuming non-automatic methods and the operators subjective evaluation.

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.

Modelling and MBS experimentation for temperature sensors

Proposals for a simplified dynamic model for a Resistance Thermometer Detector, or RTD, which is based upon a priori and a posteriori knowledge, are made. A new self-heating method of in situ sensor testing is presented. Experimentation using Multifrequency Binary Signals for both this new self-heating and the traditional external input immersion tests are described. Different transfer functions were obtained for these two testing methods. Mathematical relationships between them were determined from the laws of thermokinetics.

ECT Image Analysis Methods for Shear Zone Measurements during Silo Discharging Process

Abstract The paper covers the electrical capacitance tomography (ECT) data analysis on shear zones formed during silo discharging process. This is due to the ECT aptitude for detection of slight changes of material concentration. On the basis of ECT visualisations, wall-adjacent shear zone profiles are analysed for different wall roughness parameters. The analysis on changes of material concentration, based on ECT images, enables the calculation for the characteristic parameters of shear zones—size and material concentration inside the shear zone in a dynamic process of silo discharging. In order to verify the methodology a series of experiments on gravitational flow of bulk solids under various conditions were conducted with different initial granular material packing densities and silo wall roughness. The investigation shows that the increase in container wall roughness is an effective method for reducing the dynamic effects during the material discharging, since these effects are resulted from the resonance between hopper construction and trembling material. Such effects will damage industrial equipment in practical applications and need further investigation.

Functions and structures in measuring systems: A systems engineering context for instrumentation

Abstract The importance of Information Technology has focused attention upon that class of machines now commonly referred to as information machines. This technology has many implications. One of these is the manner in which the body of principles, upon which the technology is based, may be presented for educational purposes. An outline of the scope of teaching in measurement is given. Subsequently, it is proposed that the milieu of Systems Engineering is a pertinent, broad-based context for the teaching of instrumentation at all levels. An important justification for this view is the holistic attitude which the methodology of Systems Engineering affords. As man-machine systems are particularly important, a boundary perspective of these systems is considered. This view, which classifies inputs and outputs into one of three main types, indicates the place occupied by information within this systems environment. A reticulation of man-machine systems reveals that their structure consists of four main sub-systems. By this method, an incisive top-down view of the functions and structures of information systems in general and measurement systems in particular is achieved. In conclusion, energy bandwidth modelling is proposed as the link between modelling and information.

Image Defect Detection Methods for Visual Inspection Systems

Two texture defect detection methods for automatic visual inspection systems will be presented in this paper. They divide up an analysed texture image into non-overlapping samples, and then calculate features of each sample using statistical analysis. Finally, the clustering of those features is applied to recognize the sample as defective or non-defective. Unlike the well-known methods, the proposed schemes do not require a previous training step to collect defective and non- defective texture samples. The experimental results show that these methods are effective and more accurate than earlier methods for image texture defect detection.