Use Of Electrical Tomography Research Articles

Algorithmic methods of improving the imaging of flood embankments interior with the use of electrical tomography

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Application of Electrical Tomography Imaging Using Machine Learning Methods for the Monitoring of Flood Embankments Leaks

This paper presents an application for the monitoring of leaks in flood embankments by reconstructing images in electrical tomography using logistic regression machine learning methods with elastic net regularisation, PCA and wave preprocessing. The main advantage of this solution is to obtain a more accurate spatial conductivity distribution inside the studied object. The described method assumes a learning system consisting of multiple equations working in parallel, where each equation creates a single point in the output image. This enables the efficient reconstruction of spatial images. The research focused on preparing, developing, and comparing algorithms and models for data analysis and reconstruction using a proprietary electrical tomography solution. A reliable measurement solution with sensors and machine learning methods makes it possible to analyse damage and leaks, leading to effective information and the eventual prevention of risks. The applied methods enable the improved resolution of the reconstructed images and the possibility to obtain them in real-time, which is their distinguishing feature compared to other methods. The use of electrical tomography in combination with specific methods for image reconstruction allows for an accurate spatial assessment of leaks and damage to dikes.

Research of the geological factors of coal deposits in the south of the Far East by electrical exploration methods

Coal deposits in the south of the Far East are characterized by complex geological factors, which is due to the inclined occurrence the enclosing layers and coal seams, high pressure of underground water, the presence of water-bearing sandy-pebble and gravel-pebble sediments, the presence of numerous faults and various inclusions, the presence of island permafrost. In the exploration of deposits, the low efficiency of previously used electrical exploration methods, including electrical sounding and profiling, was noted. In this paper, it is shown that increasing efficiency in the solution of some mining and geological tasks is associated with the use of the electrical tomography method. This method has advantages in the conditions of weak differentiation of rock resistivity due to the high density of obtained parameters. With the use of electrical tomography, the tasks in the allocation of tectonic disturbances and coal seams uplift under quaternary sediments, estimation of the landslide slopes structures on the coal pit edges have been solved. Successful results were obtained in isolating the weathered layer of the bedrock, sandstone outcrops under the soil-vegetative layer in the upper part of the section, the bedrock surface on the deposit’s flanks and the covers of effusive rocks on the surface.

Geophysical modeling in gold deposit through DC Resistivity and Induced Polarization methods

Ore mining fundamentally depends on the definition of its tenor and volume, something extremely complex in disseminated mineralization, as in the case of certain types of deposits of gold and sulfites. This article proposes the use of electrical tomography for definition of a geophysical signature in terms of electrical resistivity and chargeability, in an outcrop of mineralized quartz lode at the end of an inactive gold mine. One of the targets was to analyze the continuity of the mineralized body, the occurrence of new outcrops and the applicability of the method as an auxiliary tool in mineral extraction. Three parallel lines of electrical tomography in a dipole-dipole arrangement, being orthogonal to the orientation of the gold lode, were installed in an area outside the mine. The results allowed the geophysical characterization of the mineralized zone by high resistivity (above 1000Ω.m) and high chargeability (above 30mV/V). The results of the 2D inversion models were interpolated in 3D visualization models, which allowed definition of the contour surfaces for the physical parameters measured, and the morphological pattern modeling of the mineralization. The data reveal the existence of a new lode in subsurface, localized 30m to the south of the lode outcrop. The versatility of the acquisition and data processing indicate the application potential of electrical tomography as a criterion for sampling and tenor definition in ore extraction activities, since it is objective and low cost.

Landmarks in the application of electrical tomography in particle science and technology

Selected milestones in the development and use of electrical tomography in powder conveying, slurry processing and multi-phase flow are highlighted. The ability to map concentration in opaque mixtures under process-realistic conditions was a major innovation for the method and has had far reaching implications. Subsequent developments have enabled velocity information to be abstracted resulting in the ability to measure component flux and motion.

Mapping of thin sandy aquifers by using high resolution reflection seismics and 2-D electrical tomography

Electrical tomography, which gives good results even in fairly complex geological environments, has given a new lease of life to electrical methods in hydrogeological surveys. Nevertheless, a rapid decline in resolution with increasing depth remains the main problem of the electrical methods. In the Pannonian basin in Croatia, at a test area, combining both electrical tomography and seismic reflection methods provides data that better constrain the lithological and hydrogeological model of the subsurface. Electrical tomography revealed a rather thick packet of sediments with increased resistivity at depths of 40–100 m. Using the electrical forward modelling, the existence of two different hydrogeological models was shown. The first model presupposes a reasonably homogeneous packet of sandy clays or clayey sands, and the other model presupposes the alternation between layers of clays and sands. From the hydrogeological point of view, the second model is perspective, but unfortunately, the use of electrical tomography alone does not allow the ambiguity to be resolved. The separation of these two models became possible using seismic reflection. Three seismic environments were isolated from the seismic profile treated, and the strongest reflections were discovered in the first seismic environment, which covers the depths from 40 to 100 m. It was determined that the second model is more acceptable, because these reflections are caused by lithological changes, that is, the alternations of sands and clays. The interpretation is consistent with exploratory borehole data. The conclusion is that electrical tomography gives data concerning the sediment lithology up to depths of 40 m, but at greater depths combined interpretation of electrical and seismic data constrains the subsurface model better.

Characterisation of soils with stony inclusions using geoelectrical measurements

Characterisation and sampling of coarse heterogeneous soils is often impossible using common geotechnical in situ tests once the soil contains particles with a diameter larger than a few decimetres. In this situation geophysical techniques—and particularly electrical measurements—can act as an alternative method for obtaining information about the ground characteristics. This paper deals with the use of electrical tomography on heterogeneous diphasic media consisting of resistive inclusions embedded in a conductive matrix. The adopted approach articulates in three steps: numerical modelling, measurements on a small-scale physical model, and field measurements. Electrical measurements were simulated using finite element analyses, on a numerical model containing a random concentration of inclusions varying from 0% to 40%. It is shown that for electrode spacing 8 times greater than the radius of inclusions, the equivalent homogeneous resistivity is obtained. In this condition, average measured resistivity is a function of the concentration of inclusions, in agreement with the theoretical laws. To apply these results on real data, a small-scale physical model has been built, where electrical measurements were conducted both on the model and on each phase. From these laboratory measurements, a very satisfying estimation of the percentage of inclusions has been obtained. Finally, the methodology applied to a real experimental site composed of alluvial fan deposits made of limestone rocks embedded in a clayey matrix. The estimated percentage of rock particles obtained via electrical measurements was in accordance with the real grain size distribution.

Dynamic Imaging of Process Plant Reactors and Separators Using Electrical Process Tomography

The use of electrical tomography is beginning to find application in industrial processes as a measurement tool for modelling, model verification and on-line monitoring and diagnosis. The method employs simple sensors arranged on the periphery of process reactors that contact the process fluid. Electrical excitation allows to collect information that can be used to deduce the distribution of electrical properties (such as conductivity, or dielectric constant) within the reactor. These can in turn be related to reactant-product concentration profiles within the reactor, provided that such components exhibit inherent differences in electrical properties. A particular attribute of electrical systems is their ability to make measurements rapidly. The author reported the most recent developments in the application of electrical capacitance and electrical resistance tomography to a selection of process systems [3-5]. The objective was to illustrate the capabilities of the method. The rapid data collection process facilitates observation of kinetic processes. Laboratory and industrial studies of the following systems have been presented:- gas-liquid and liquid-liquid stirred tanks (tank design and scale up, mixing kinetics);- solid-liquid stirred tanks (tank design and scale up, crystallisation and precipitation);- gas-liquid bubble columns (flow monitoring and control of interfacial area);- solid-liquid cyclonic separators (fluid dynamic code development, on-line plant monitoring);- solid-liquid separation (cycle time in product washing);- autoclave polymerisers (reaction pathways and endpoints). Prospects for the integration of advanced visualisation and modelling tools with chemical reactor models have been discussed. Future goals were identified, including the possible use of chemical species mapping.