Movable Electrode Research Articles

Investigation of anode shaping process during co-rotating electrochemical machining of convex structure on inner surface

A novel co-rotating electrochemical machining method is proposed for fabricating convex structures on the inner surface of a revolving part. The electrodes motion and material removal method of co-rotating electrochemical machining are different from traditional electrochemical machining. An equivalent kinematic model is established to analyze the novel electrodes motion, since the anode and cathode rotate in the same direction while the cathode simultaneously feeds along the line of centres. According to the kinematic equations of the electrodes and Faraday’s law, a material removal model is established to simulate the evolution of the anode profile in co-rotating electrochemical machining. The simulation results indicate that the machining accuracy of the convex structure is strongly affected by the angular velocity ratio and the radius of the cathode tool. An increase of the angular velocity ratio can improve the machining accuracy of a convex structure. A small difference in the radius of the cathode tool will cause changes in the shape of the sidewalls of the convex structure. The width of the cathode window affects only the width of the convex structure and the inclination α of the sidewall. A relation between the width of the cathode window and the width of the convex structure was obtained. The formation process for a convex structure under electrochemical dissolution was revealed. Based on the simulation results, the optimal angular velocity ratio and cathode radius were selected for an experimental verification, and 12 convex structures were simultaneously fabricated on the inner surface of a thin-walled revolving part. The experimental results are in good agreement with the simulation results, which verifies the correctness of the theoretical analysis. Therefore, inner surface co-rotating electrochemical machining is an effective method for fabricating convex structures on the inner surface of a revolving part.

Numerical investigation on transient arc characteristics and anode surface temperature considering the electrode movement

This work investigates the transient anode temperature and plasma parameters considering the electrode movement and the arc expansion. A transient self-consistent model is established using the dynamic mesh approach. Two cases with different maximum arc currents, representing various anode activity, have been studied. The simulations predict significant changes in spatial distribution of species densities, electron temperature and anode surface temperature in case with the anode spot formation. Furthermore, the influence of opening velocity on the plasma parameters has been studied numerically. The model was validated by comparison with experimental data for anode surface temperature as well as spectrally filtered arc images. Results of this comparison are presented and discussed.

Combined Control System for the Coordinates of the Electric Mode in the Electrotechnological Complex “Arc Steel Furnace-Power-Supply Network”

To stabilize the electrical mode of an arc steelmaking furnace in the initial stages of melting, it is advisable to use a high-speed current-limiting system, in addition to the traditional electrode movement control system. This system is implemented by including the primary winding of the furnace transformer choke, controlled by thyristors. The use of such a system, on the one hand, reduces the negative impact of the arc steel furnace on the the power supply network operation and, on the other, affects the operation of the electrode movement system, built on the principle of an impedance regulator. In order to analyze the mutual influences between such systems, a mathematical model for the power supply and control system of the arc steelmaking furnace was created. The developed model can work in real time, which corresponds to the world trends of modern control system synthesis for complex technological objects. In the created model, the work of the combined control system with different approaches to the formation of the control effect in the high-speed circuit and the effect of the combined control system on the power supply system of the ASF are analyzed.

Channel-Wise Average Pooling and 1D Pixel-Shuffle Denoising Autoencoder for Electrode Motion Artifact Removal in ECG

This paper presents a channel-wise average pooling and one dimension pixel-shuffle architecture for a denoising autoencoder (CPDAE) design that can be applied to efficiently remove electrode motion (EM) artifacts in an electrocardiogram (ECG) signal. The three advantages of the proposed design are as follows: (1) In the skip connection layer, less memory is needed to transfer the features extracted by the neural network; (2) Pixel shuffle and pixel unshuffle techniques with point-wise convolution are used to effectively reserve the key features generated from each layer in both the encoder and decoder; (3) Overall, fewer parameters are required to reconstruct the ECG signal. This paper describes three deep neural network models, namely CPDAELite, CPDAERegular, and CPDAEFull, which support various computational capacity and hardware arrangements. The three proposed structures involve an encoder and decoder with six, seven, and eight layers, respectively. Furthermore, the CPDAELite, CPDAERegular, and CPDAEFull structures require fewer multiply-accumulate operations—355.01, 56.96, and 14.69 million, respectively—and less parameter usage—2.69 million, 149.7 thousand, and 55.5 thousand, respectively. To evaluate the denoising performance, the MIT–BIH noise stress test database containing six signal-to-noise ratios (SNRs) of noisy ECGs was employed. The results demonstrated that the proposed models had a higher improvement of SNR and lower percentage root-mean-square difference than other state-of-the-art methods under various conditions of SNR.

Analysis of the Toughness of the Vertical Position GMAW Welding on Steel ST 42 with Electrode Spiral Movement Pattern

This study aims to determine the toughness value of vertical position GMAW welding on ST 42 steel with a spiral electrode motion pattern. This study consisted of ST 42 steel, cut to the standard ASTM E23 specimen as many as 20 samples. The toughness value of the GMAW welding results in a vertical position, describes the strength and toughness of the material in making ST 42 steel joints. The results of the ST 42 steel impact test with spiral; the average value of impact toughness was 135.375 Joule with an impact value of 0.2461 (J/mm²), while without treatment the average impact toughness was 183.975 Joule with an impact value of 0.3345 (J/mm²). Thus, it can be concluded that the impact toughness of ST 42 steel with a spiral electrode movement pattern is smaller than the impact toughness without welding joint treatment means that the toughness of ST 42 steel without a connection is stronger than using a welded joint with a spiral electrode motion pattern.

Evaluating the Safety of Simultaneous Intracranial Electroencephalography and Functional Magnetic Resonance Imaging Acquisition Using a 3 Tesla Magnetic Resonance Imaging Scanner.

BackgroundThe unsurpassed sensitivity of intracranial electroencephalography (icEEG) and the growing interest in understanding human brain networks and ongoing activities in health and disease have make the simultaneous icEEG and functional magnetic resonance imaging acquisition (icEEG-fMRI) an attractive investigation tool. However, safety remains a crucial consideration, particularly due to the impact of the specific characteristics of icEEG and MRI technologies that were safe when used separately but may risk health when combined. Using a clinical 3-T scanner with body transmit and head-receive coils, we assessed the safety and feasibility of our icEEG-fMRI protocol.MethodsUsing platinum and platinum-iridium grid and depth electrodes implanted in a custom-made acrylic-gel phantom, we assessed safety by focusing on three factors. First, we measured radio frequency (RF)-induced heating of the electrodes during fast spin echo (FSE, as a control) and the three sequences in our icEEG-fMRI protocol. Heating was evaluated with electrodes placed orthogonal or parallel to the static magnetic field. Using the configuration with the greatest heating observed, we then measured the total heating induced in our protocol, which is a continuous 70-min icEEG-fMRI session comprising localizer, echo-planar imaging (EPI), and magnetization-prepared rapid gradient-echo sequences. Second, we measured the gradient switching-induced voltage using configurations mimicking electrode implantation in the frontal and temporal lobes. Third, we assessed the gradient switching-induced electrode movement by direct visual detection and image analyses.ResultsOn average, RF-induced local heating on the icEEG electrode contacts tested were greater in the orthogonal than parallel configuration, with a maximum increase of 0.2°C during EPI and 1.9°C during FSE. The total local heating was below the 1°C safety limit across all contacts tested during the 70-min icEEG-fMRI session. The induced voltage was within the 100-mV safety limit regardless of the configuration. No gradient switching-induced electrode displacement was observed.ConclusionWe provide evidence that the additional health risks associated with heating, neuronal stimulation, or device movement are low when acquiring fMRI at 3 T in the presence of clinical icEEG electrodes under the conditions reported in this study. High specific absorption ratio sequences such as FSE should be avoided to prevent potential inadvertent tissue heating.

A Refined Closed-Form Solution for the Large Deflections of Alekseev-Type Annular Membranes Subjected to Uniformly Distributed Transverse Loads: Simultaneous Improvement of Out-of-Plane Equilibrium Equation and Geometric Equation

The Alekseev-type annular membranes here refer to annular membranes fixed at outer edges and connected with a movable, weightless, stiff, con-centric, circular thin plate at inner edges, which were proposed originally by Alekseev for bearing centrally concentrated loads. They are used to bear the pressure acting on both membranes and plates, which was proposed originally in our previous work for developing pressure sensors. The pressure is applied onto an Alekseev-type annular membrane, resulting in the parallel movement of the circular thin plate. Such a movement can be used to develop a capacitive pressure sensor using the circular thin plate as a movable electrode plate of a parallel plate capacitor. The pressure applied can be determined by measuring the change in capacitance of the parallel plate capacitor, based on the closed-form solution for the elastic behavior of Alekseev-type annular membranes. However, the previous closed-form solution is unsuitable for annular membranes with too large deflection, which limits the range of pressure operation of the developed sensors. A new and more refined closed-form solution is presented here by improving simultaneously the out-of-plane equilibrium equation and geometric equation, making it possible to develop capacitive pressure sensors with a wide range of pressure operations. The new closed-form solution is numerically discussed in its convergence and effectiveness and compared with the previous one. Additionally, its beneficial effect on developing the proposed capacitive pressure sensors is illustrated.

Detailed investigation of sinusoidal vibration on triboelectric energy harvester

ABSTRACT The triboelectric energy harvester (TEH) could power small electronic devices, including temperature sensors, GPS trackers, accelerometers, and humidity sensors. An experimental and simulation investigation on the harvesting of sinusoidal mechanical vibration utilizing a triboelectric mechanism is presented in this article. According to numerical results, the amount of energy harvested depends on many input elements such as movement of the upper electrode, external resistance, phase angle, contact area, and thickness of the dielectric layer. The influences of the dual parameters, including the dielectric thickness, contact area, external resistance, phase angle, and vibration frequency on electrical output, were investigated systematically. The stability and durability test are performed for fabricated TEH. Simultaneously, a bridge rectifier has been used to convert produced A.C. signals into D.C. signals. The output voltage is stored in capacitors of various sizes (0.47, 3.3, 10, 22, 47 µF) with no load resistances. The feasibility of the developed TEH is proved by lighting up 35 red Light-Emitting Diodes (LEDs).

ელექტრული ღუმლის ელექტროდების გადაადგილების მართვის სისტემის ოპტიმიზაცია

It’s known that the efficient operation of electrical appliances used in production significantly improves the quality and quantity of products. Competent control of technological processes is especially important for such a heavy industry as metallurgical production, where one of the most important issues is the optimal control system for electric motors of moving electrodes, which in turn ensures the required dynamics of arc power control and high productivity. The existing arc power control systems do not fully meet the basic requirements, such as insufficient sensitivity of the regulating parameter, speed and reliability of the electrode movement motor control system. The study of electric motor control systems is an important scientific and technical task in this regard. The optimization of the electric motor control system for moving the electrodes of an electric arc furnace based on the use of logic in control is discussed.

Simulation of Scrap Melting Process in an AC Electric Arc Furnace: CFD Model Development and Experimental Validation

The electric arc furnace (EAF) is a critical steelmaking facility that melts the scrap by the heat produced from electric arc and burners. Simulation and optimization of EAF scrap melting are of great interest to the steel industry, which helps to improve product quality and production efficiency. However, the relevant computational fluid dynamics (CFD) modeling of this process has not been reported so far. The present study established a three-dimensional (3D) integrated CFD model to simulate the scrap melting process in the alternating current (AC) EAF. The scrap melting model was developed to simulate the dynamic scrap melting and collapse based on the dual-cell approach and the stack approach. The electric arc model and the coherent jet model were introduced and integrated with the scrap melting model to estimate the electrical and chemical energy inputs need for melting. The CFD-compatible Monte Carlo method and electrode regulation strategy were developed respectively to predict the arc radiative heat dissipation and track the instant electrode movement. The experiments for the scrap melting by both electric arc and coherent jet burner were designed and implemented in the industry-scale NLMK 150-ton EAF for the model validation. The proposed model was applied to simulate the scrap melting process under the NLMK EAF typical run, and the scrap melting behavior, the electric arc performance, and the burner performance were evaluated and discussed based on the simulation results.

Analysis of Ferroelectric Negative Capacitance-Hybrid MEMS Actuator Using Energy–Displacement Landscape

We propose an energy-based framework to analyze the statics and dynamics of a ferroelectric negative capacitance-hybrid Microelectromechanical System (MEMS) actuator. A mapping function that relates the charge on the ferroelectric to displacement of the movable electrode, is used to obtain the Hamiltonian of the hybrid actuator in terms of displacement. We then use graphical energy-displacement and phase portrait plots to analyze static pull-in, dynamic pull-in and pull-out phenomena of the hybrid actuator. Using these, we illustrate the low-voltage operation of the hybrid actuator to static and step inputs, as compared to the standalone MEMS actuator. The results obtained are in agreement with the analytical predictions and numerical simulations. The proposed framework enables straightforward inclusion of adhesion between the contacting surfaces, modeled using van der Waals force. We show that the pull-in voltage is not affected, while the pull-out voltage is reduced due to adhesion. The proposed framework provides a physics-based tool to design and analyze negative capacitance based low-voltage MEMS actuators.

Three-Dimensional Droplet Manipulation with Electrostatic Levitation.

An active and precise method for three-dimensional (3D) droplet manipulation is introduced. By modulating the local electrostatic force acting on droplets in carrier oil between needle plate electrodes, the vertical motion of droplets can be controlled, including the droplet levitation at the interface between the carrier oil and the air. Levitated droplets can be translated horizontally with high efficiency by the motion of the needle electrode. With controllable local deformation on the flexible plate electrode, selective manipulation can be realized for multiple droplets. Applying the manipulation method proposed, a platform is built and various droplet handling, such as transport, merging, and mixing, is performed effectively. Complex droplet transport trajectories are achieved by moving the needle electrode. The droplet transport velocity can reach up to 37 mm/s. The introduced method has fundamental advantages of avoiding cross-contamination between droplets, enhancing the flexibility, eliminating the transport track constraint, and lowering costs with straightforward and precise droplet manipulation.

Reconsideration of energy measurement of spark discharge using different triggering methods and inductance loads

A series of electrostatic sparks at different energies are triggered by different methods in testing the minimum ignition energy (MIE) of dust clouds. It is necessary to investigate the difference between actual spark energies and MIEs under different triggering methods. A multi-energy spark generating circuit combined with high-voltage relay (HVR) triggering and electrode movement (EM) triggering was set up to study the effects of triggering types and inductance loads. The first current peak was proposed together with damping ratio and angular frequency of spark current to evaluate the reliability of the experimental results. Results showed that the deviation of spark energy release efficiency between the two triggering types is about 5%–25% when the storage energy was 34 mJ, 110 mJ, 340 mJ and 1100 mJ, which was not enough to cause the difference in the magnitude of MIE. The MIEs of clouds of lemon powder and sea buckthorn powder are consistent using the two triggering types. But the MIE of clouds of lycopodium triggered by EM without inductance is higher than that triggered by HVR. It indicates different triggering types may lead to different MIE results when testing fine dust even if the actual released energy is almost the same. The spark energy release efficiency without inductance is greater than or equal to that with inductance. However, the MIE of lycopodium clouds dropped from 75–90 mJ with no inductance, to 8–10 mJ with a 1 mH inductance. The MIEs of clouds of lemon powder and sea buckthorn powder showed similar trends.

A Further Theoretical Study of Capacitive Pressure Sensors Based on Thin Film Elastic Deflection and Parallel Plate Capacitor: Refined Closed-Form Solution and Numerical Calibration.

The capacitive pressure sensor based on thin film elastic deflection and a parallel plate capacitor uses a non-conductive elastic annular thin film centrally connected to a conductive, rigid, flat, concentric-circular thin plate as a pressure sensing unit. On application of pressure, the non-conductive thin film deflects elastically, which in turn moves the conductive thin plate (as a movable upper electrode plate of the parallel plate capacitor) towards the lower electrode plate, resulting in a change in the capacitance of the capacitor. Therefore, the applied pressure can be determined by measuring the capacitance change, based on the closed-form solution for the elastic behavior of the annular thin film under pressure. Such capacitive pressure sensors are more suitable for large-sized sensors such as those used for building-facade wind pressure measurements, etc. In this paper, a further theoretical study of such capacitive pressure sensors is presented. The newly presented, more refined closed-form solution can greatly reduce the output pressure error under the same input capacitance, in comparison with the previously presented closed-form solution. A numerical example of how to use the resulting closed-form solution to numerically calibrate input–output characteristics is given for the first time. The variation trend of pressure operation ranges and input–output characteristics with important parametric variations, which can be used for guiding the design of such capacitive pressure sensors, is investigated.

A Mismatch Correction Method for Electrode Offset in Electrical Impedance Tomography

Electrical impedance tomography (EIT) has attracted research interests in imaging of brain function, detection of breast cancer, monitoring of lung function and other medical fields. For EIT, its image reconstruction is largely affected by variation of electrode placement arranged around the detected object. Note that electrode offset is unavoidable in some medical applications, leading to low-quality reconstructed images or even failure of reconstruction. In this paper, a novel method is proposed to improve reconstruction quality in case of electrode offset. By identifying which electrode moves, mismatched boundary voltage caused by movement of electrode is corrected. After mismatch correction, image reconstruction is conducted with total generalized variation regularization method. To demonstrate performance of the proposed method in suppressing impact of electrode offset on reconstruction, extensive work is carried out. Mismatch corrections for four models under a series of counterclockwise or clockwise movements of a certain electrode are studied. The reconstruction results show that the proposed method can effectively improve the image quality under electrode offset. Even in presence of larger electrode offset and noise, reconstructed images have been greatly improved. Quantitative evaluation is also conducted by calculating relative blur radius (RBR). It is shown that RBR values are much closer to 1 compared with results under mismatch conditions. Image reconstruction when two electrodes move is also investigated which further validate the performance of the proposed method. This method is potential for mismatch correction in some medical applications.

A novel flexible plasma array for large-area uniform treatment of an irregular surface

In this work, we demonstrate a flexible multi-pin plasma generator with movable electrodes, which can change the shape of the electrode array freely, and then provide a large-area uniform plasma for the treatment of surfaces of different shapes. Discharge characteristics including U–I waveforms and discharge images and sterilization performance under three different electrode configurations (flat–flat, flat–curve, curve–curve) are investigated. Very similar results are acquired between the flat–flat configuration and the curve–curve configuration, which is much better than that under flat–curve configuration. This flexible multi-pin plasma generator offers a simple method to treat different irregularly shaped surfaces uniformly with a single device. Moreover, this device provides a foundation for developing a self-adaption large-scale uniform plasma generator by further introducing automatic adjustment of the position of every electrode driven by motors with discharge current feedback in the following study. Thus it will promote the applications of atmospheric-pressure cold plasmas significantly.

A Mathematical Model of Electrical Arc Furnaces for Analysis of Electrical Mode Parameters and Synthesis of Controlling Influences

The synthesis of a real-time model of the electric mode of an arc steelmaking furnace is shown. This model is based on the method of medium-voltage and can be used to analyze the impact of the arc steelmaking furnace on the supply network at different stages of the melting process at different control systems of the electromechanical electrode movement system, and to create model-predictive control systems of electrode movement, when control using hardware in the loop technology. To implement the chosen method, the dynamic arc resistance was used. The last was obtained on the basis of the averaged experimentally taken volt-ampere characteristics of the arc. In paper was proposed its approximation as a current function and arc length. The simulation results obtained using the created model for different operation modes of the arc steelmaking chipboard for a system with a traditional regulator of the electrode movement system are demonstrated.

Motion-enhancement assisted digital image correlation of lithium-ion batteries during lithiation

For the first time, a motion enhancement and registration technique (MERt) – an advanced phase based motion enhancement method combined with an optical flow based digital image correlation process is used to investigate batteries. This, in combination with the non-invasive investigative nature of X-ray computed tomography, makes for a powerful tool to examine the mechanism behind (de)lithiation of Li-ion cells. Through MERt, which magnifies the displacement of electrodes and tracks any internal changes, it is generally observed that the electrode expands outwards, but once encountering the solid barrier that is the cell casing, the electrode has nowhere to expand but inwards, which is why the electrode deformations initiate at the cell core. The technique clearly affirms that the greatest movement of electrodes during lithiation occurs at pre-existing inflection points in the jelly roll, which are a result of the manufacturing process, and eventually leads to the large deformations observed in this and previous works. MERt also indicates a contortion of the cell casings during lithiation which may be caused by the uneven expansion of the electrodes, but requires further studies to confirm.

DeepRTSNet: Deep Robust Two-Stage Networks for ECG Denoising in Practical Use Case

In this paper, we develop a low-cost cellular internet of medical things (IoMT)-based electrocardiogram (ECG) recorder for monitoring heart conditions and used in practical cases. In order to remove noise from signals recorded by these non-clinical devices, we propose a cloud-based denoising approach that focuses on utilizing deep neural network techniques in the time-frequency domain through the two stages. Accordingly, we exploit the fractional Stockwell transform (FrST) to transfer the ECG signal into the time-frequency domain and apply the deep robust two-stage network (DeepRTSNet) for noise cancellation. Due to the practical use case, the various heart physiologies and noise levels in different amplitudes and frequencies are needed to be robust against wide-range noises in actual conditions. We utilize the MIT-BIH Apnea-ECG database (APNEA-ECG) with several different heart physiologies. Next, the different noises consisting of muscle artifacts (MA), baseline wander (BW), and electrode motion (EM) from the MIT-BIH Noise Stress Test Database (NSTDB) and random noise, are added to the signals. The main focus of the noise generation part is the fast Fourier transformation (FFT) of the simulated noisy signal and the practical noisy signal has a maximum cross-correlation to gain a better morphological resemblance between realistic signals and the prepared datasets. Based on the results, DeepRTSNet outperforms prior learning-based methods and conventional non-learning approaches in terms of signal-to-noise ratio (SNR), root mean square error (RMSE), and percent root mean square difference (PRD). Moreover, outcomes reveal that DeepRTSNet has an extraordinary performance with a certain amount of further complexity than others.

Spatial Planetary Movements for Multi-Axis EDM

Multi-axis electrical discharging machining (EDM) is the most commonly used manufacturing method for shrouded blisks. However, debris is difficult to be evacuated from a discharge gap, thus severely affecting the machining efficiency. Spatial planetary movements of a tool electrode can generate a non-uniform flow field in the discharge gap, promoting the evacuation of debris. This paper proposes a spatial planetary movement method for a feeding path of spatial line segments. Screw theory is used to derive the kinematics of a spatial planetary movement, and the coordinate increments of each axis in an interpolation period can be calculated. Then a multi-axis EDM machine can be controlled to drive a tool electrode to realize the spatial planetary movement. Machining experiments are carried out to explore the influences of the spatial planetary movement parameters on the machining performance of multi-axis EDM. Experiment results show that spatial planetary movements can improve the machining efficiency of multi-axis EDM, and the increase in the radius and speed of spatial planetary movements can further improve the machining efficiency. The machining efficiency can be increased by 51.62% and 50.44% respectively.