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Further tests of EVT4 data acquisition system for electrical capacitance tomography are presented. The modular system, which can have up to 32 channels with an individual analogue to digital converter, was designed to ensure small uncertainty of capacitance measurement at high speed of imaging. The system’s performance in the context of 3D imaging was experimentally verified. In particular, we show that the measurement of changes in capacitance due to a small change of an electric permittivity distribution for the most distant electrodes in a suitably designed 3D sensor is possible using our system. Cross-plane measurements together with the measurements for the pairs of most distant electrodes are essential for accurate reconstruction of 3D distributions. Due to sensitivity of capacitance measurements obtained in the hardware, the measurements for all electrode pairs can be used in the inverse problem – the system of equations can be extended. Although the numerical condition number of a matrix of such a system is high, image reconstruction is possible from the data obtained in our system. The results of 3D image reconstruction for simple test objects are shown.

• New experimental data on the horizontal plug to slug transition flow is reported. • Drift flux analysis is performed in horizontal plug to slug transition flow. • Good agreement between current data against existing models and correlations was confirmed. A thorough understanding of the behaviour of the transition from plug to slug flow is imperative based on the fact that the transition can trigger an abrupt radial pressure variation. This can bring about major vibrations to the pipeline and also lead to big differences in pressure gradient and wall temperature. Unfortunately, the transition from plug to slug flow is poorly understood due to the scarce availability of experimental data. Furthermore, a considerable amount of research on the transition from plug to slug flow in the literature is based on an air–water system. In this work, the transition behaviour from plug to slug flow in a horizontal pipeline was experimentally investigated using electrical capacitance tomography (ECT). Working fluids are air–silicone oil. The work was carried out over a range of liquid and gas superficial velocities of 0.05–0.47 m/s and 0.05–4.7 m/s, respectively. Wave growth and wave characteristics mechanisms were observed to be responsible for the transition from plug to slug flow based on the obtained experimental results. Both liquid and gas superficial velocities have a major influence also on these mechanisms. The drift flux parameters for the transition from plug to slug flow was determined. A reasonably good agreement was observed from the comparison between present experimental data against hitherto published empirical models and correlations. [ABSTRACT FROM AUTHOR]

Electrical capacitance tomography (ECT) has been developed for imaging permittivity distribution of two-phase flows in a pipe or vessel with high temporal resolution. The spatial resolution of ECT is relatively low due to its soft-field, ill-posed, and ill-conditioned nature. So far, there is no comprehensive analysis of the spatial resolution of ECT for complex two-phase flows. To assess the merits of ECT systematically, 2-D modeling is carried out based on fluid-field and electrostatic-field coupling simulation for liquid–solids two-phase flows. The real permittivity distribution and the corresponding capacitance measurements can be obtained simultaneously. The effect of the number of electrodes, the mesh used for reconstruction, and the initialization method for the Landweber iteration algorithm on image quality are investigated. In terms of the correlation coefficient between the reconstructed permittivity distribution and the real permittivity distribution obtained from the coupling simulation model, the accuracy and the stability of reconstructed images are quantitatively evaluated. Furthermore, the sensitivity matrices and point spread functions calculated without capacitance measurements are used to compare the performance of ECT sensors and validate the results with capacitance measurements from the coupling simulation. The two methods, with and without capacitance measurements, are used to evaluate the change in spatial resolution of ECT with a different number of electrodes. [ABSTRACT FROM AUTHOR]

• Void fraction was measured immediately after a sudden expansion using capacitance tomography. • A correlation was proposed to model the void fraction behavior occurring right after an expansion. • The proposed correlation improved the predictive ability over existing correlations. In this work, electrical capacitance tomography (ECT) was used to measure the changes in void fraction immediately after a sudden expansion for horizontally flowing refrigerant R-134a. The two-phase flow behavior occurring in the sudden expansion was also analyzed using a high-speed camera for two different area ratios of 0.145 and 0.44. Void fractions determined from correlations found in the literature were compared with experimental measurements made immediately after a sudden expansion. It was found that none of the correlations examined could represent the behavior of the void fraction immediately after the expansion. A modified correlation was proposed to model the void fraction behavior occurring right after the expansion. This new correlation was able to predict the void fraction within a ± 20% error band when compared with experimental data at mass velocities of 50 to 250 kg m−2s−1 and area ratios of 0.145 and 0.44. [ABSTRACT FROM AUTHOR]

Image reconstruction algorithm plays a vital role in the practical application of electrical capacitance tomography. For the research of image reconstruction algorithm, the LBP, SVD, ART, Landweber algorithm and Tikhonov regularization algorithm are compared in this study. Four kinds of multiphase flow patterns are simulated based on MATLAB simulation platform, and the effects of reconstructed images are compared in three aspects: image error, correlation coefficient and calculation time. The analysis results show that the image reconstruction speed of the direct algorithm is better than the iterative algorithm, while the image reconstruction quality is worse than the iterative algorithm. [ABSTRACT FROM AUTHOR]

Brain Electrical Capacitance Volume Tomography (Brain ECVT) is a new technique that realizes real-time volumetric imaging of dynamic changes in electrical activity of the brain and allows total interrogation of the whole volume inside a helmet-shaped sensor. The technique has been used for investigating numerous brain functional abnormalities, including brain tumors, based on permittivity different from the tumor case, as compared to the normal brain. However, interpretation of the conventional Brain ECVT image is not practical for clinical purposes, as the image resolutions are high in the cortical area and lower in the middle region. The technique provides relatively good sensitivity when the tumor is located near the cortex. In this study, we developed a novel method, namely the average subtraction technique, to process the reconstructed image of the brain obtained by Brain ECVT. The technique generates a three-dimensional intracranial distribution of permittivity that correlates with the electrical activity map of the brain with improved resolution in the center region of the brain. The technique provides better insight into brain intracranial electrical activity, which is quite distinctive when there is tumor development inside the brain. The technique may lead to better detection of brain tumors inside the brain based on the electrical activity scan. [ABSTRACT FROM AUTHOR]

As a powerful visualization tomography technique, electrical capacitance tomography (ECT) method, which reconstructs the permittivity distribution in a sensing domain according to the measured capacitance data, has been widely used in different industry scenarios. However, the image reconstruction in ECT is an ill-posed problem, and its application is plagued by low-quality reconstructions, and seeking for a robust algorithm to reduce reconstruction errors and artifacts is crucial. To increase the reconstruction quality, a novel cost function is built for imaging, in which the $L_{1-2}$ norm is designed as a regularizer for encoding the sparsity prior of imaging objects. The ant lion optimizer (ALO) algorithm and the alternating direction method of multipliers (ADMMs) with the Douglas–Rachford splitting (DRS) method and the soft thresholding algorithm as powerful optimizers for minimizing the subproblems are combined into a novel solver for solving the built cost function more effectively. Simulation and experimental results indicate that the proposed imaging technique can improve the quality of reconstructed images. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The characteristics of flow configuration in pipes are very important in the oil industry due to its role in governing equipment design. In vertical risers, many flow configurations could be observed such as bubbly, slug, churn, and annular flow. In this project, two tomographic techniques have been applied simultaneously to the flow in a vertical riser: the Electrical Capacitance Tomography (ECT) technique and the Capacitance Wire Mesh Sensor (WMS) technique. The employed pipe diameter was 50mm and the superficial studied velocities were 0.06-3.0m/s for gas and 0.06-0.4m/s for oil. Several techniques have been used to analyze the output data of the two tomography techniques such as time series of cross-sectional averaged void fraction, Probability Density Function (PDF), image reconstruction, and liquid hold-up profile. The averaged void fractions were calculated from the output signal of the two measurement techniques and plotted as functions of the superficial velocity of the gas. The flow patterns were identified from the PDF of the averaged void fraction. In addition, it was found that both tomographic techniques are reliable in identifying the flow regimes in pipes. [ABSTRACT FROM AUTHOR]

For the problems of missing edges and obvious artifacts in Electrical Capacitance Tomography (ECT) reconstruction algorithms, an image reconstruction method based on a multiscale dual-channel convolutional neural network is proposed. Firstly, the image reconstructed by Landweber algorithm is input into the convolutional neural network, and four scales are selected for feature extraction. Feature unions are used across the scales to fuse the information of the output layer with feature maps. To improve the imaging accuracy, two frequency channels are designed for the input image. The middle layer of the network consists of two fully convolutional structures. Convolutional layers and jump connections are designed separately for different channels, which greatly improves the network's ability to extract feature information and reduces the number of feature maps required for each layer. The number of network layers is shallow, which can speed up the network training, prevent the network from falling into local optimum, and ensure the effective transmission of image details. Simulation experiments are carried out for four typical dual media distributions. The edges of the reconstructed image are smoother and the image error is smaller. It effectively resolves the lack of edges in the reconstruction image and reduces the image edge artifacts in the ECT system. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sensor design is important for electrical capacitance tomography (ECT) that is to be used for a particular application and for generating high-quality images from the measured data. An ECT sensor with long electrodes is commonly used to obtain stable and reliable measurement signals and to ensure the quality of 2D cross-sectional images, but it neglects the effect of electrode length on the entire 3D image. To analyze the effect of electrode length on the measured signals, sensitivity distribution and the quality of reconstructed images, especially the distortion of 3D images, ECT sensors with different electrode lengths of 5, 7, 10, 20 and 30 mm are designed and fabricated. The electrodes are mounted on the internal surface of the ECT sensor wall to eliminate the negative effect of the wall. A dual-electrode excitation strategy is chosen to enhance the signal intensity. The results show that the reconstructed 3D images of the measured objects, which can be divided into three parts, are stretched in the axial direction and narrowed in the radial direction because of the axial average effect, and longer electrodes result in a more serious problem. Comprehensive analysis of the performance of the ECT sensors with different electrode lengths, including the measured signals, sensitivity distribution and reconstructed 3D images, concludes that an ECT sensor with an electrode length of 10 mm is recommended. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin University of Science & Technology is the property of Journal of Harbin University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The temporal and cross‐sectional distributions of particles in a 127 mm diameter fluidized bed have been obtained using a new generation, high‐speed electrical capacitance tomography. Two planes of eight electrodes were used and mounted at 160 and 660 mm from the gas distributor which was a 3 mm thick porous plastic plate (maximum pore size of 50‐70 μm). 3 mm diameter, nearly‐spherical polyethylene granules made up the bed. Experiments at sampling frequencies of 200‐2000 cross‐sections per second and gas superficial velocities from just below the minimum fluidization to 83% above minimum fluidization velocities were used. The time series of the cross‐sectional average void fractions have been examined both directly and in amplitude and frequency space. The last two used probability density functions and power spectral densities. The information gathered shows that the fluidized bed was operating in the slugging mode, which is not surprising given the size of the particles. It has been found that an increase in the excess gas velocity above the minimum fluidization velocity resulted in an increase in the mean void fraction, an increase in the length and velocity of the slug bubbles as well as the bed height, and a slight decrease in the slug frequency. The results are presented in a level of detail suitable for comparison with later numerical simulation. [ABSTRACT FROM AUTHOR]

• New data for pressure drop, void fraction and flow pattern in a vertical pipe using air–silicone oil are reported. • The comparison between the PDF of void fraction obtained from ECT, WMS and DP cell showed good agreement for churn flow. • The PDF of void fraction from the outputs of the ECT, WMS and DP cell can be used to predict churn flow with confidence. • The experimental data have good agreements with empirical correlation models. New data for pressure drop, void fraction and flow pattern in a vertical riser using air–silicone oil as the system fluid are reported in this work. A differential pressure cell (DP cell) was used to measure the pressure drop. Also, void fraction data were recorded simultaneously by an electrical capacitance tomography (ECT) and wire mesh sensor (WMS). The observed flow patterns are the spherical cap bubble, slug and churn flows. However, only the slug flow without the presence of churn flow is seen within the transition line as predicted by the map. The characteristic probability density function (PDF) derived from void fraction data was used to determine the flow patterns. A comparison between present experimental results and the air–water data reported in the literature was carried out and various levels of agreement were achieved. The PDFs obtained from the DP cell signals for spherical cap bubble and slug flows significantly differ from those derived from the ECT and WMS outputs. Current void fraction and pressure gradient results were compared with the values predicted by ten empirical correlations selected from the literature. Statistical tools such as Mean Square Error (MSE), Root Mean Square Error (RMSE) and Mean Absolute Percentage Error (MAPE) were applied in the comparison. The Greskovich and Cooper correlation gave the least MSE, RMSE and MAPE values of 0.0007908, 0.013 and 3.05%, respectively for slug flow. [ABSTRACT FROM AUTHOR]

To solve the underdetermined problem and the mismatches of position and size of the objects caused by the ill-posed sensitivity matrix in electrical capacitance tomography (ECT) image reconstruction, an alternating direction approximate newton (ADAN) method is developed. Based on the alternating direction method of multipliers (ADMMs), this algorithm utilizes the Bregman operator splitting (BOS) algorithm to segment the total variation (TV) regularization model. An approximation to Newton’s method, in which a term in Newton’s hessian is replaced by a Barzilai–Borwein (BB) approximation, is used to solve the subproblems after segmentation, and the complete convergence proof and the stability analysis of the algorithm are provided. The quantitative analysis of reconstruction results of the ADAN, Landweber, modified Landweber, Newton, and ${l}_{1}$ regularization methods shows that the average relative error (RE) of ADAN in the reconstruction of ten flow images is 0.2199, which is lower than that of reconstructed by the other four algorithms. The average correlation coefficient (CC) of the reconstructed images of ADAN is higher than that reconstructed by the ${l}_{1}$ regularization, Newton, modified Landweber, and Landweber methods, which are 0.8539, 0.6792, 0.6251, 0.6545, 0.6665, and 0.6614, separately. Moreover, under the same iteration stopping condition, the iteration time of ADAN is the shortest. [ABSTRACT FROM AUTHOR]

• Monitoring and controlling particle distribution in pneumatic conveyance by ECT-AIS. • Permittivity distribution homogeneity was determined by spatial standard deviation. • Homogeneous downstream particle distribution was controlled by airflow injection. • Spatial standard deviation of permittivity evaluated by LBP and Landweber alogithm. • Spatial mean permittivity in ECT sensors were evaluated with normalized pressures. Electrical capacitance tomography with airflow injection system (ECT-AIS) has been developed for controlling particle distribution in pneumatic conveyance in order to maintain homogeneous downstream particle distribution ε n do t + τ with a delay time τ even under inhomogeneous upstream particle distribution ε n up t . ECT-AIS is composed of two ECT sensors for monitoring ε n up t and for evaluating ε n do t + τ after injecting airflow. The airflow is injected to the conveyance pipe by activating a solenoid valve of airflow injection system (AIS) to control the homogeneous ε n do t + τ in the case that the spatial standard deviation of permittivity distribution at the upstream ECT sensor ε SD up t which is calculated from ε n up t and the spatial mean permittivity 〈 ε n up 〉 t is greater than the threshold value δ. With this developed ECT-AIS, three different experiments are performed under different particle loading ratios (ϕ = 0.25, 0.50 and 0.75) with air flow rate Q a = 0.75 kg/s, 0.50 kg/s and 0.25 kg/s. As ε n up t is homogeneous, ε n do t + τ is also homogeneous. While ε n up t was inhomogeneous, ε n do t + τ was homogeneously distributed due to airflow injection. To evaluate the homogeneity of ε n do t + τ , the spatial mean permittivity 〈 ε n up 〉 t in upstream sensor is compared with 〈 ε n do 〉 t + τ in downstream sensor and the two results were evaluated with the measured pressures p n up t and p n do t . As a results, ε SD do t + τ is less than or equal to δ so that 〈 ε n do 〉 t + τ is homogeneous after airflow injection. Based on Darcy–Weisbach equation, as the particles are homogeneous, the pressure is lower than that in inhomogeneous distribution. According to the relationship between mean permittivity and pressure, ε n do t + τ is successfully controlled in homogeneous conditions by ECT-AIS. [ABSTRACT FROM AUTHOR]

A review is presented of measurement techniques to characterise dispersed multiphase flows, which are not accessible by means of conventional optical techniques. The main issues that limit the accuracy and effectiveness of optical techniques are briefly discussed: cross-talk, a reduced signal-to-noise ratio, and (biased) data drop-out. Extensions to the standard optical techniques include the use of fluorescent tracers, refractive index matching, ballistic imaging, structured illumination, and optical coherence tomography. As the first non-optical technique, a brief discussion of electrical capacitance tomography is given. While truly non-invasive, it suffers from a low resolving power. Ultrasound-based techniques have rapidly evolved from Doppler-based profiling to recent 2D approaches using feature tracking. The latter is also suitable for time-resolved flow studies. Magnetic resonance velocimetry can provide time-averaged velocity fields in 3D for the continuous phase. Finally, X-ray imaging is demonstrated to be an important tool to quantify local gas fractions. While potentially very powerful, the impact of the techniques will depend on the development of acquisition and measurement protocols for fluid mechanics, rather than for clinical imaging. This requires systematic development, aided by careful validation experiments. As theoretical predictions for multiphase flows are sparse, it is important to formulate standardised 'benchmark' flows to enable this validation. [ABSTRACT FROM AUTHOR]

• A new imaging method is proposed for the ECT reconstruction. • Data-driven prior and sparsity-driven prior are injected into the imaging model. • Ensemble extreme learning machine is developed to predict the data-driven prior. • A new optimizer is developed to solve the built imaging model. • The effectiveness of the proposed imaging technique are numerically validated. Electrical capacitance tomography (ECT) is a potential measurement technology for industrial process monitoring, but its applicability is generally limited by low-quality tomographic images. Boosting the performance of inverse computing imaging algorithms is the key to improving the reconstruction quality (RQ). Common regularization iteration imaging methods with analytical prior regularizers are less flexible in dealing with actual reconstruction tasks, leading to large reconstruction errors. To address the challenge, this study proposes a new imaging method, including reconstruction model and optimizer. The data-driven regularizer from a new ensemble learning model and the analytical prior regularizer with the focus on the sparsity of imaging objects are combined into a new optimization model for imaging. In the proposed ensemble learning model, the generalized low rank approximations of matrices (GLRAM) method is used to carry out the dimensionality reduction for decreasing the redundancy of the input data and improving the diversity, the extreme learning machine (ELM) serves as a base learner and the nuclear norm based matrix regression (NNMR) method is developed to aggregate the ensemble of solutions. The singular value thresholding method (SVTM) and the fast iterative shrinkage-thresholding algorithm (FISTA) are inserted into the split Bregman method (SBM) to generate a powerful optimizer for the built computational model. Its comparison to other competing methods through numerical experiments on typical imaging targets demonstrates that the developed algorithm reduces reconstruction error and achieves much more improvement in imaging quality and robustness. [ABSTRACT FROM AUTHOR]

Research into the application of Electrical Capacitance Tomog-raphy (ECT) carried out in the Laboratory of the Aircraft En- gines Division at Warsaw University of Technology has shown that it is applicable to recognition of various flames. Several cases were tested using the ECT system and the system suc- cessfully created cross sectional images of premixed and diffu- sion flames. Studies were then conducted which significantly increased the functionality of the system. This article describes experimental studies that afforded insight into the effects of the degree of ionization generated during the combustion process on the changing signal of the ECT system. Research was carried out in an experimental stand consisting of a burner, 6 and 12 electrodes capacitance sensors and an opti- cal spectrometer. Burner injection was used to obtain stability of combustion. Two rotameters were installed in the inlet of the burner. The ow rate of air and methane was used to de- termine the composition of the combustible mixture formed in the mixing chamber. A grating spectrometer was used to per- form a detailed analysis of combustion processes and to detect various types radicals. This experimental test focused on mea- suring chemiluminescence intensities and possible correlations of the OH*, CH*, C2* and H2O with air/methane ratio. The data from the ECT system and optical spectrometer was then analyzed. It was found that the strong correlations between the peak intensity of OH*, CH*, C2* and H2O in the reaction zone to the equivalence ratio could be used to investigate the local ame stoichiometry. [ABSTRACT FROM AUTHOR]

We present a Relevance Vector Machine (RVM) based algorithm for electrical capacitance tomography (ECT) applications that can concurrently provide image reconstruction results and uncertainty estimates about the reconstruction. To illustrate the RVM operation in ECT, we simulate typical ECT scenarios, making explicit the connection between the reconstructed pixel values and the corresponding uncertainty estimates in each case. We compare the RVM reconstruction performance with that of the Iterative Landweber Method (ILM) and the least absolute shrinkage and selection operator (LASSO) in all the considered scenarios. The results show that, in addition to the key advantage of providing uncertainty measures, RVM can achieve similar reconstruction results with either lower or similar computational complexity. [ABSTRACT FROM AUTHOR]

The linear back projection (LBP) algorithm is often used for real-time online image reconstruction of electrical capacitance tomography (ECT) due to its high speed. However, due to the fact that the image reconstruction of ECT is a nonlinear ill-posed inverse problem, reconstructed images obtained by the LBP algorithm that simplifies ECT image reconstruction as a linear problem, tend to have distortion and can only be used for qualitative observation. In this paper, a deep fully-connected neural network, which improves the imaging quality of the LBP algorithm by compensating its imaging results is proposed. Instead of simplifying the ECT image reconstruction as a linear problem, our proposed compensated LBP algorithm uses a deep neural network to map the nonlinear relationship from capacitance to permittivity distribution. Furthermore, the difference between the capacitance regarding the permittivity distribution reconstructed by the LBP algorithm and the actual capacitance is used as the input of the network while the difference between the reconstructed permittivity distribution and the actual permittivity distribution is used as the output of the network. The results of the network can be used to compensate the image reconstruction results of the LBP. This strategy makes the ECT image reconstruction need only to deal with a support interval significantly smaller than that of the original ECT image reconstruction problem and is helpful to suppress the nonlinearity to be trained. Both the training and testing results based on simulation data instances and experimental data show that the proposed compensation network has a great improvement on image reconstruction results of the LBP algorithm. In addition, the computation load is comparable to the original LBP algorithm. [ABSTRACT FROM AUTHOR]

Electrical Capacitance Tomography (ECT) has been developed for many years and made great progresses. Successful applications of ECT depend on the accuracy and speed of image reconstruction. In this paper, we propose a new image reconstruction method based on deep neural network. The proposed neural network mainly consists of three parts, i.e. a forward problem network, an inverse problem network and a permittivity prediction network. Compared to previous reconstruction algorithms, the benefit of our method is that it can not only reconstruct the object shape, but also predict its permittivity value with the preset resolution which is desired in many multiphase flow applications. In experiment, 10000 frames of simulation data and additional measured capacitance data were used. The results show that the proposed method can reconstruct images more accurately than typical iterative methods with real permittivity values of objects predicted correctly, and reduce the computational cost to about 2.24 seconds per frame for an image resolution of 200*200. [ABSTRACT FROM AUTHOR]

Pressurised circulating fluidised bed (PCFB) is a new technology for coal/biomass combustion and gasification. To design, optimise and scale-up of PCFBs, it is necessary to understand the complex gas-solids flow characteristics. In this research, electrical capacitance tomography (ECT) technique, pressure measurement, and computational particle fluid dynamic (CPFD) simulation were combined for the first time to investigate the hydrodynamic behaviour of a pilot-scale PCFB test rig. The custom single- and dual-plane ECT sensors in the riser bottom and cyclone dipleg, provided the real-time cross-sectional particle distribution and circulation flux in a non-intrusive way. Pressure measurements in low and high frequency, revealed the full-loop pressure distribution and local flow regime respectively. In addition, CPFD simulations based on Wen-Yu/Ergun and EMMS (energy-minimization multi-scale) drag model, were performed and evaluated by the experiments. The results demonstrate that (i) gas-solids flow in the PCFB riser shows the non-uniform distribution both axially and radially; (ii) EMMS based simulation predicts flow behaviour in agreement with the experiments, while Wen-Yu/Ergun model significantly over-estimates the particle dispersion and circulation flux; (iii) the elevated operating pressure enhances the gas-solids mixing, by demonstrating the more uniform particles axial distribution and development of radial "core-annular" structure towards the riser bottom and (iv) the elevated operating pressure improves the particle circulation flux, with the improvement limited by the saturated carrying capacity of the PCFB test rig. Full-loop pressure and particles volume fraction distribution. Unlabelled Image • A full-loop pressurised circulating fluidised bed of pilot-scale was simulated by CPFD method. • Electrical capacitance tomography was applied to investigate the dense flow regime in the pressurised CFB. • Wen-Yu/Ergun and EMMS drag model were implemented and compared in the simulation. • A comprehensive comparisons among ECT measurement and CPFD simulation are given. • Effects of pressure on the complex gas-solids flow characteristics are given and discussed. [ABSTRACT FROM AUTHOR]

Dynamic analyses have been applied to the temporal signals from an Electro Capacitance Volume Tomography instrument located near mid-height on the riser of an industrial-scale cold-flow circulating fluidized bed to characterize gas-solids flow behavior in the riser. Twelve capacitance electrodes surround the cylindrical riser over a height of 1.3 m. The instrument used a neural network deconvolution algorithm to determine the spatially resolved solids fraction recorded at 52 Hz. Experiments were carried out over a range of gas and solids flows in the transport regime using a Geldart Group B bed material, high density polyethylene with mean particle size of 880 μm. The radial solids distribution was found to vary from one-time step to the next between profiles typical of laminar and turbulent flow. The duration of time spent in each of these flow profiles depended upon the operating regime – dilute, core-annular, or fast fluidized bed. The chaotic structure of the temporal data was characterized using the three conventional approaches: the first 4 moments from the distribution of signal in time, system memory parameters from the autocorrelation function and the Hurst exponent, and analysis of the correlation entropy and correlation dimension of the attractor. These signal analysis techniques were used to clearly distinguish differences between different transport operating regimes. Specifically, it was experimentally observed that a riser transitions from core annular flow profile to dilute and dense regimes via increasing the frequency of short term transients to either dilute or dense flow profiles, respectively. A regime map was generated based upon these dynamics using solids flux and gas velocity axes. Fast fluidized, core annular, and dilute each exhibited different degree of dynamic characteristics typical of fluid dominated or particle compromising behavior. It should be noted that the magnitude for the different statistics? was in the same range regardless of the regime, it was the radial profile for the statistic that changed and subsequently identified that there was a change in the regime. Finally, a reduced regime map was developed consisting of plotting the gas velocity normalized by the upper transport velocity versus the solids flux normalized by the saturation carrying capacity. The use of this reduced plot allowed the data from widely different conditions to be plotted and compared on the same graph. Note that in many instances, some of the statistics identified the operating point as being in one regime while others indicated that it was in another indicating a transition region between dilute or core annular regimes and between the core annular and fast fluidization regimes. This now provides a tool that can be used to optimize process performance, identify changes in operating states, or replicate process dynamics during process scaling or changing operating parameters. Unlabelled Image • Dynamic analyses have been applied to the temporal signals from an ECVT device. • The radial solids distribution varied between profiles of laminar and turbulent flow. • The duration of time spent in each of these flow profiles depended upon the operating regime. • A regime map was generated based upon these dynamics. • Fast fluidized, core annular, and dilute each exhibited different characteristics. [ABSTRACT FROM AUTHOR]

In the pharmaceutical industry, fluidized beds are typically used for pellets drying, coating and granulation. The gas–solids flow characteristic in the process plays an important role to control the heat and mass transfer as well as the end-point product quality. Therefore, it is necessary to investigate the flow characteristics based on advanced measurement technologies. In this research, electrical capacitance tomography (ECT) sensor with eight electrodes was used to investigate the pharmaceutical fluidized bed drying process with different operation conditions. Key process parameters including solids concentration, particle moisture and capacitance signals in the process are given and analysed based on the ECT sensor. In addition, the fluidized bed process with Wurster tube is also investigated based on this ECT sensor. The effect of Wurster tube on the hydrodynamic behaviour and the dominant frequency spectrum distribution in the chamber were analysed based on fast Fourier transform. Test results reveal that process moisture change can be addressed from the raw capacitance of adjacent electrode pair combined with calibration model. Experimental result also indicates that ECT technology can provide useful information for process monitor in a fluidized bed dryer. [ABSTRACT FROM AUTHOR]

The electrical capacitance tomography (ECT) is an image-based technology which has been widely used for gas–solid two-phase flow measurement. The solid-phase electrification is an inevitable phenomenon during pneumatic conveying. To reduce the influence of medium electrification on the ECT image reconstruction, a composite sensitivity matrix (CSM) which takes into account the effect of charge electrification is developed in this paper, so that the image reconstruction error can be well suppressed. This paper first analyzes how the medium electrification affects ECT sensitivity field from the perspective of electromagnetic theory. The CSM is then derived accordingly. Simulations and physical experiments are carried out to validate the proposed method. The experimental results show that the relative error and the correlative coefficient of the reconstructed images have been significantly improved comparing with that in traditional approaches. The results support the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

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Particle volume flow rate Q PLUG · in plug flow through a cross section of horizontal pipe has been accurately measured by a combination of dual electrical capacitance tomography sensor and plug flow shape model (dECT-PFSM). The plug flow shape model divides the trapezoidal shape of the plug flow into three flow regions which are Tip, Filling, and Tail regions. The plug flow volume V PLUG is estimated by velocity and length which are measured in each region by the normalized permittivity signal changes obtained from the dECT images under the plug flow in the trapezoidal shape. The path time difference of the plug flow Δ t PLUG is also measured. The total volume flow rate of the plug flow is subsequently obtained from the sum of the plug flow volume of the three regions divided by Δ t PLUG. Consequently, the volume flow rate of the plug flow obtained by dECT-PFSM Q ECT, PFSM · is compared with that of high-speed camera (HSC) as reference and conventional cross-correlation (CC) method. The absolute error E abs of the proposed method is less than that of the CC method. The dECT-PFSM method is, therefore an affordable noninvasive technique for accurate determination of the volume flow rate of the plug flow. Unlabelled Image • Particle volume flow rate measurement by dual ECT combined plug flow shape model. • Particle plug flow is divided into three regions: Tip, Filling and Tail regions. • Measurement of velocity and volume flow rate of plug flow using permittivity signal. • Volume flow rate shows good agreement with high speed camera's result. • Absolute error of our method is less than conventional Cross-correlation method. [ABSTRACT FROM AUTHOR]

The electrical capacitance tomography (ECT) technique has been extensively studied for real-time tomographic imaging of various industrial processes. Due to the ‘soft-field’ and under-determined problems in the image reconstruction, the tomographic images of ECT are usually low in the spatial resolution when compared with its radioactive counterparts, i.e. $\gamma $ -ray tomography and computed tomography. This paper presents an ECT sensor that consists of 8 external electrodes and 8 internal electrodes, with enhanced image quality at the center of imaging region and better accuracy on phase fraction measurement. The internal electrodes are placed on cross planes inside the investigated vessel. In this way, the signal-to-noise ratio of measurement channels as well as image quality are improved. Numerical simulations show that the proposed sensor can achieve better reconstructed images than a conventional 12-electrode sensor. In addition, the phase fraction calculation using ECT data can also benefit from the internal electrodes and corresponding measurements, which is an important parameter for multiphase flow processes. [ABSTRACT FROM AUTHOR]

Image reconstruction plays a key role in the application of electrical capacitance tomography (ECT). Although many different algorithms have been developed in the past, it is often difficult to obtain satisfactory images in all imaging regions by the use of a single algorithm due to the soft-field nature of ECT. This motivated us to develop a novel ECT image reconstruction strategy, in which a high-quality image can be obtained by combining the images reconstructed by two different algorithms via a graph cut method. By doing so, it is possible to retain the advantage of each algorithm for specified imaging regions and improve the quality of the whole image. This strategy was verified both numerically and experimentally for two widely used ECT reconstruction algorithms, i.e., linear backprojection and Tikhonov regularization. The results for stationary objects as well as gas–solid fluidized beds demonstrated that this graph-cut-based combination strategy presents a promising approach for ECT image reconstruction. [ABSTRACT FROM AUTHOR]

Pneumatic conveying systems have become a standard technique for the transport of bulk materials such as powdery or granulates. The spatial dependence of the material density and the stream velocity in such transport systems require a volumetric measurement principle for flow measurement. In this paper we analyse the capability to estimate the volume fraction from capacitive sensing data using electrical capacitance tomography (ECT). In particular, we investigate the capability of back-projection type imaging algorithms. The ill-posed nature of the imaging problem of ECT require the incorporation of prior knowledge in the design of the estimator. We analyse the different flow profiles in pneumatic conveying in order to generate specific sample-based prior information to improve the estimation performance and robustness. We discuss the construction of different linear image reconstruction algorithms and present a framework, which allows a detailed statistical analysis of the estimator performance. Simulation studies show the estimation behaviour of different algorithms with respect to the incorporated prior information. We demonstrate, that the incorporation of specific prior knowledge leads to an improved estimator behaviour; for example, reduced variance and unbiased estimates. We implemented laboratory experiments in order to analyse the presented approach for the application in real pneumatic conveying processes. We demonstrate the improved robust estimation behaviour by means of comparative reconstruction results obtained with different algorithms and priors. Furthermore, the uncertainty of the estimated volume fraction is analysed in steady state conveying processes. Hereby, it is demonstrated, that appropriate prior information improves the estimation performance also for measurements coming from real pneumatic conveying processes, making ECT a suitable tool for the volume fraction estimation in such transport systems. [ABSTRACT FROM AUTHOR]

Wurster fluidised bed is commonly used for coating pellets in the pharmaceutical industry. Normally, the control in a Wurster fluidised bed for coating is based on point-based measurement, that is, pressure and optical probes. However, the point-based measurement methods only provide local flow information and cannot reveal the cross-sectional flow dynamics characteristics and it is difficult to control the whole process with limited data. In this paper, electrical capacitance tomography (ECT) is applied to reconstruct the solids distribution in a lab-scale Wurster fluidised bed for coating pellets and the measurements are used in a control loop of the process. The flow regime is identified from the ECT images using a simple but efficient approach. The objective of control is to keep stable minimum fluidisation and avoid undesired flow regime in the region between the outside wall and the Wurster tube, such as intermittent, plug and defluidisation. To achieve this target, a PID controller is applied to keep a low volume fraction in the annular region by adjusting the fluidisation air rate, and bang-bang control is applied to a peristaltic pump used for spraying coating solutions based on the detected flow regime. It has been found that the proposed control scheme based on the ECT measurement is effective for keeping a stable flow regime, reducing the degree of pellets agglomeration and avoiding defluidisation. [ABSTRACT FROM AUTHOR]

With the increase of capacity, most of the circulating fluidized beds (CFB) risers are constricted to have rectangular cross section. Therefore, it is important to find out the cross-sectional aspect ratio effect on the gas-solids flow characteristics. In this study, a lab-scale CFB with two rectangular risers, which have the aspect ratio of 1:1 and 3:1, respectively, were studied by the electrical capacitance tomography (ECT), with the aided of pressure measurements and computational particle fluid dynamics (CPFD) simulation. Key issues related with ECT sensor design and image reconstruction, such as sensitivity map and excitation frequency, are also discussed. The results show that ECT image quality is affected by the sensitivity map and excitation frequency, and high excitation frequency and voltage are not equivalent of high image quality. In the riser bottom region, cross-sectional aspect ratio has big effect on ECT measured particle distribution and pressure drop, fewer particles are brought away from the bottom when the aspect ratio is larger. Multiple bubbles exist in the bottom region at Ve= 2.7 m/s, and bubble size decreases in the rectangular riser with larger cross-sectional aspect ratio. Static bed height influences the bubble behaviour that bubbles with smaller size scattered around and behave collapse or coalescence in the moving process when the static bed height is high. [ABSTRACT FROM AUTHOR]

In this paper, an electrostatic-immune AC-based electrical capacitance tomography (ECT) is developed to visualize the gas-solid flow inside the circulating turbulent fluidized bed (C-TFB) reactor. A fractal gas distributor based on fractal self-similarity theory is used to improve the particle distribution by re-distributing the intake gas. Experiments are carried out on a cold model of lab-scale C-TFB to investigate the effect of the fractal gas distributor using the electrostatic-immune ECT. Experimental results show that the particle concentrations with the fractal gas distributor are higher than those without the fractal gas distributor under identical operation conditions, indicating that the fractal gas distributor is favorable to enhance the upward movement of particles inside the C-TFB reactor. Moreover, the radial particle distribution with the fractal gas distributor is more even at a certain area of C-TFB, indicating that the fractal gas distributor can improve the radial uniformity of C-TFB within its active region. Unlabelled Image • An electrostatic-immune ECT is developed to visualize the C-TFB reactor. • The particle distribution in C-TFB has a "core-annulus" shape during the E-Mode experiments. • Fractal gas distributor can enhance the upward movement of particles in C-TFB. • Fractal gas distributor can improve the radial uniformity of C-TFB. [ABSTRACT FROM AUTHOR]

In the present study, a novel fluidized bed with the internal separator was developed to achieve the self-sustained preheating of pulverized coal. In the developed internal fluidized bed combustor (IFBC), the pulverized coal could be heated up to 850 °C–950 °C by its partial combustion. The hot pulverized coal was fed into the furnace of pulverized coal (PC) boiler for complete combustion. Combining PC boiler with the IFBC could achieve easer ignition and reduce nitrogen oxides emission for the low-rank coal. To verify the feasibility and optimize the design and operation of the IFBC system, the cold experiments were performed in a small-scale IFBC for continuous feeding with Group A particles. The effect of superficial air velocity on the operational performance and gas-solid flow characteristics in the IFBC was investigated by electrical capacitance tomography, pressure measurement as well as visual observation. The experiments showed that, the IFBC could operate stably in the case of continuous feeding when superficial air velocity ranged from 1.5 m/s to 2.25 m/s, in which the material output rate was steady, nearly equal to the material input rate. With the increase in the superficial air velocity, more solids remained in the standpipe and the discharge pattern of standpipe shifted from the continuous discharge to the intermittent discharge, thereby resulting in the unstable operation. The solids intermittent dump referred to a typical feature of the intermittent discharge, characterized by a sawtooth function. Unlabelled Image • A internal fluidized bed combustor(IFBC) was applied in coal preheating technology • The IFBC could operate stably at the superficial air velocity of 1.5–2.25 m/s • The discharge patterns in the standpipe significantly affect the IFBC's operation • The fluctuation of solids intermittent dump is similar to sawtooth wave [ABSTRACT FROM AUTHOR]

Electrical capacitance tomography (ECT) is one of non-invasive visualization techniques which can be used for industrial process monitoring. However, acquiring images trough 3D ECT often requires performing time consuming complex computations on large size matrices. Therefore, a new parallel approach for 3D ECT image reconstruction is proposed, which is based on application of multi-GPU, multi-node algorithms in heterogeneous distributed system. This solution allows to speed up the required data processing. Distributed measurement system with a new framework for parallel computing and a special plugin dedicated to ECT are presented in the paper. Computing system architecture and its main features are described. Both data distribution as well as transmission between the computing nodes are discussed. System performance was measured using LBP and the Landweber’s reconstruction algorithms which were implemented as a part of the ECT plugin. Application of the framework with a new network communication layer reduced data transfer times significantly and improved the overall system efficiency. [ABSTRACT FROM AUTHOR]

Reliance on harmless and renewable resources to mitigate process environmental footprint has become increasingly important for the design and operation of sustainable processes. One challenge that is prevalent in marine water surface contamination concerns treatment and recovery from oil spills where efforts are needed to design emergency units adapted to marine conditions. Potential candidates are naturally-grown porous loofa (bio-foam) materials which can be integrated in floating units transportable to the contamination area. For this purpose, a hexapod platform motion simulator was employed to emulate sea-driven floating movements of a column packed with two loofa bio-foam packings (dense and open-cell samples) and operated in cocurrent gas-liquid upflow mode. The column hydrodynamic behaviour was monitored by means of capacitance wire mesh sensors and electrical capacitance tomography for various inclination and rolling parameters. In the case of dense bio-foam packing, the relatively even distribution of gas and liquid in the vertical bed tended to degrade as the bed tilted up to 15°. Column rolling prompted fluid displacements in bed crosswise planes inducing notable amplitude oscillations of the local liquid saturation. Kerosene exhibited a strong foaming behavior with promotion of earlier inception of pulsing flow as a function of column inclination as compared to water. [ABSTRACT FROM AUTHOR]

Electrical capacitance tomography (ECT) is a multiphase flow detection technology, which has the advantages of nonradioactive, noninvasive, and on-line visualization measurements. In ECT measurements, the digital phase sensitive demodulation (PSD) plays an important role in guaranteeing the accuracy of small capacitance measurements. Generally, the clamping circuit is implemented to protect the A/D converter. In the measuring circuit, a programmable gain amplifier is usually employed to expand the dynamic range of PSD. However, the measured signal may exceed the measurement range from time to time, which induces the signal clamping effect. In this case, the digital PSD will present large errors in the capacitance measurements. In consideration of the frequency spectrum characteristic of the clamped signal, two digital PSD methods have been proposed. The proposed methods have been implemented in a field programmable gate array based measurement system. The experimental results show that the proposed multisine PSD method could expand the dynamic range by a factor of 5, at a relatively low error, i.e., ≤2%. [ABSTRACT FROM AUTHOR]

Electrical capacitance tomography (ECT) is a potent image-based measurement technology for monitoring industrial processes, but low-quality images generally limit its application scope and measurement reliability. To increase the precision of reconstruction, in this study, a data-driven plug-and-play prior abstracted by a deep convolutional neural network (DCNN) and the sparseness prior of imaging objects, in form of regularizers, are jointly leveraged to generate a potent imaging model, in which the L1 norm of the mismatch error acts as a data fidelity term (DFT) to weaken the sensitivity of estimation result to noisy input data. The DCNN is embedded into the split Bregman (SB) technique to generate a powerful computing scheme for solving the built imaging model and the fast iterative shrinkage-thresholding algorithm (FISTA) is applied to solve the sub-problems efficiently. Extensive numerical results verify that the proposed imaging technique has competitive reconstruction ability and better robustness in comparison with the state-of-the-art methods. This study demonstrates the validity and efficacy of the proposed algorithm in reducing reconstruction error. Most importantly, the research outcomes verify that the data-driven plug-and-play prior and the sparseness prior can be jointly embedded into the imaging model, leading to a remarkable decline in reconstruction error. [ABSTRACT FROM AUTHOR]

This paper presents highly robust, novel approaches to solving the forward and inverse problems of an Electrical Capacitance Tomography (ECT) system for imaging conductive materials. ECT is one of the standard tomography techniques for industrial imaging. An ECT technique is nonintrusive and rapid and requires a low burden cost. However, the ECT system still suffers from a soft-field problem which adversely affects the quality of the reconstructed images. Although many image reconstruction algorithms have been developed, still the generated images are inaccurate and poor. In this work, the Capacitance Artificial Neural Network (CANN) system is presented as a solver for the forward problem to calculate the estimated capacitance measurements. Moreover, the Metal Filled Fuzzy System (MFFS) is proposed as a solver for the inverse problem to construct the metal images. To assess the proposed approaches, we conducted extensive experiments on image metal distributions in the lost foam casting (LFC) process to light the reliability of the system and its efficiency. The experimental results showed that the system is sensible and superior. [ABSTRACT FROM AUTHOR]

A Wurster fluidized bed, widely used in the coating process of the pharmaceutical industry, is modeled to investigate the characteristics of gas-solids flow, concerning the effect of Wurster tube and operating parameters. Two main methods used in this research are computational fluid dynamic (CFD) simulation and electrical capacitance tomography (ECT) measurement. The CFD model is based on the kinetic theory of granular flow (KTGF). The drag model based on the energy-minimization multi-scale (EMMS) method is applied and compared with Wen-Yu and Gidaspow models. Key process parameters, including the solids volume fraction, solids velocity, bubble diameter and pressure drop, are analyzed and verified by the measurement results. Both the CFD simulation and ECT measurement results provide valuable information revealing the hydrodynamic characteristics in the dense-phase zone, and the combination of these two techniques provides a good method to investigate the flow field in Wurster fluidized beds. For the lab-scale Wurster fluidized bed, the results of Wen-Yu and Gidaspow drag models have a good agreement with the ECT measurement. The design of the Wurster tube has significant effects on the flow characteristics. To guarantee the solids circulation in the bed while avoiding the non-uniform coating or undesired agglomeration, optimized parameters of the tube geometric dimensions and fluidization conditions are chosen to improve the solids circulation efficiency and the product quality based on the CFD simulation and ECT measurement results. The sensitivity analysis gives the guiding direction for further optimization of a lab-scale Wurster fluidized bed. Unlabelled Image • Fluidized bed with Wurster tube is modeled based on the kinetic theory of granular flow. • A unique ECT sensor is used to investigate the gas-solid flow in the system. • Different drag model including EMMS and Wen-Yu model are used in the simulation. • A comprehensive comparison among measurement and CFD simulation is given and discussed. [ABSTRACT FROM AUTHOR]

Flow stability is a key issue to be addressed by the development of dense phase pneumatic conveying. Flow patterns are closely related to flow stability. From the view of experimental materials, angle of repose, packing density and tapped density and flowability results show that the tested pulverized coal approximated a Geldart's group C powder with strong cohesion. This study contributes with a computational particle fluid dynamic (CPFD) simulation which is based on the numerical solution of continuity and momentum balance equations in a three-dimensional (3-D) horizontal pipeline. A novel correction model was developed, describing interaction among particles and between fluid and particles decided by the experiment mentioned before. The drag force model was done with the parameter sensitivity analysis. The errors of particle velocity profiles and pressure drop predicted by the CPFD approach were below 5% for the stable cases. What's more, the six different flow patterns were predicted by the CPFD approach embedded in the correction model, which was confirmed by electrical capacitance tomography (ECT) in our experimental facility. With the help of our correction model and some suggestions, the CPFD approach may help people to predict dense-phase pneumatic conveying of cohesive powders, such as coal. Unlabelled Image • Multiphase particle-in-cell model is used to predict dense phase pneumatic conveying. • Pressure drop and velocity profiles show good agreement with experiments. • An improved model was proposed to give the right simulation results. • The CPFD method was validated. [ABSTRACT FROM AUTHOR]

For the research presented in this paper, hybrid organic-inorganic materials were prepared using a modified sol-gel reaction. Hybrid organic-inorganic compounds were synthesized in ethanol using methylmethacrylate (MMA), SiO2 nanoparticles, and 3-trimetoxi-silil-propilmethacrylate (TMSPM) as coupling agent. For the deposition of thin films, the spincoating method was used. The electrical measurements of dielectric thin films were done using a metalinsulator- metal (MIM) devices fabricated to study the dielectric constant of the films as function of frequency (measured at 1 MHz). Electrical results show a weak trend of the dielectric constant of the hybrid films with different MMA molar ratio. More importantly, the PMMA-SiO2 hybrid films showed a higher dielectric constant than SiO2 and PMMA layers, due to the presence of additional C-O-C bond. For the calculation of dielectric permittivity, the thickness of thin films was measured using cross-section SEM micrographs and the value of dielectric permittivity was calculated using electrical capacitance formula. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the problem of low image reconstruction accuracy of electrical capacitance tomography (ECT), this paper proposes an ECT image reconstruction method based on Long Short-Term Memory Network (LSTM). Based on the analysis and research of LSTM and ECT image reconstruction problems, the image reconstruction problem is transformed into a time series problem that LSTM can handle. Firstly, this paper proposes an image based encoding method of "rows" and "columns", which organizes the images into N*M matrices according to "rows" and "columns" respectively. These N rows are considered as output "time series" with time steps. Then, according to the above method, the reconstructed images obtained using the Landweber method and setting images are encoded separately. Thus, the input and output sample libraries of the neural network are obtained. At the same time, the LSTM model was constructed and trained according to the "row" and "column" encoding methods. The above trained models are respectively used for inference, and the inference results are post-processed and fused, and the fusion results are used as the final ECT reconstruction image. Finally, simulation experiments were conducted. The experimental results have shown that the image error and correlation coefficient of the reconstructed image proposed in this paper are superior to Landweber algorithm, Tikhonov algorithm and convolutional neural network (CNN). This also provides a new approach and means for ECT image reconstruction algorithms. • This study proposes an improved image reconstruction algorithm of ECT. • The image reconstruction problem is transformed into a time series problem that LSTM can handle. • This paper proposes an image based "row" and "column" encoding methods. • The LSTM model was constructed and trained according to the "row" and "column" encoding methods. • The above trained models were used for inference and fusion to obtain the final ECT reconstructed image. [ABSTRACT FROM AUTHOR]