Wire Electrodes Research Articles

Comparison of drilling of Inconel 625 by AWJM and WEDM

PurposeThis study aims to comparatively analyze the cut parts obtained as a result of cutting the Ni-based Inconel 625 alloy, which is widely used in the aerospace industry, with the wire electro-discharge machining (WEDM) and abrasive water jet machining (AWJM) methods in terms of macro- and microanalyses.Design/methodology/approachIn this study, calipers, Mitutoyo SJ-210, Nikon SMZ 745 T, scanning electron microscope and energy dispersive X-ray were used to determine kerf, surface roughness and macro- and microanalyses.FindingsConsidering the applications in the turbine industry, it has been determined that the WEDM method is suitable to meet the standards for the machinability of Inconel 625 alloy. In contrast, the AWJM method does not meet the standards. Namely, while the kerf angle was formed because the hole entrance diameters of the holes obtained with AWJM were larger than the hole exit diameters, the equalization of the hole entry and exit dimensions, thanks to the perpendicularity and tension sensitivity of the wire electrode used in the holes drilled with WEDM ensured that the kerf angle was not formed.Originality/valueIt is known that the surface roughness of the parts used in the turbine industry is accepted at Ra = 0.8 µm. In this study, the average roughness value obtained from the successful drilling of Inconel 625 alloy with the WEDM method was 0.799 µm, and the kerf angle was obtained as zero. In the cuts made with the AWJM method, thermal effects such as debris, microcracks and melted materials were not observed; an average surface roughness of 2.293 µm and a kerf of 0.976° were obtained.

Non-transferring arc and wire additive manufacturing: microstructure, mechanical properties and bulk texture evolution of deposits

PurposeThis study aims to demonstrate a modified wire arc additive manufacturing (AM) named non-transferring arc and wire AM (NTA-WAM). Here, the build plate has no electrical arc attachment, and the system’s arc is ignited between tungsten electrode and filler wire.Design/methodology/approachThe effect of various deposition conditions (welding voltage, travel speed and wire feed speed [WFS]) on bead characteristics is studied through response surface methodology (RSM). Under optimum deposition condition, a single-bead and thin-layered part is fabricated and subjected to microstructural, tensile testing and X-ray diffraction study. Moreover, bulk texture analysis has been carried out to illustrate the effect of thermal cycles and tensile-induced deformations on fibre texture evolutions.FindingsRSM illustrates WFS as a crucial deposition parameter that suitably monitors bead width, height, penetration depth, dilution, contact angle and microhardness. The ferritic (acicular and polygonal) and lath bainitic microstructure is transformed into ferrite and pearlitic micrographs with increasing deposition layers. It is attributed to a reduced cooling rate with increased depositions. Mechanical testing exhibits high tensile strength and ductility, which is primarily due to compressive residual stress and lattice strain development. In deposits, ϒ-fibre evolution is more resilient due to the continuous recrystallisation process after each successive deposition. Tensile-induced deformation mostly favours ζ and ε-fibre development due to high strain accumulations.Originality/valueThis modified electrode arrangement in NTA-WAM suitably reduces spatter and bead height deviation. Low penetration depth and dilution denote a reduction in heat input that enhances the cooling rate.

Electrostatic Dust Analyzer for Dust Transport Measurements on the Lunar Surface

Lunar dust charging and transport is a more than five-decade-old problem. A high-fidelity and flight-qualified Electrostatic Dust Analyzer (EDA) has been developed to measure the charge, velocity, mass (size), and flux of electrostatically lofted dust particles on the lunar surface. Recent laboratory findings have greatly advanced our fundamental understanding of the dust-charging and -lofting mechanisms, providing critical constraints to the design of the EDA instrument. EDA consists of two identical dust trajectory sensor (DTS) units on both ends of the instrument with a deflection field electrode (DFE) unit lying in between. When a dust particle enters the instrument, charge signals induced on four arrays of wire electrodes in the two DTS units determine the total charge of the dust particle and its trajectory passing through the instrument from which the dust velocity vector is measured. The mass (size) is derived from the deflection of the dust trajectory by the DFE. A dust campaign was performed to characterize the instrument’s performance. The results meet or exceed the requirements. EDA has achieved high Technology Readiness Level 6. EDA measurements are important for assessing the dust environment on the lunar surface and its subsequent impact on crew safety and the operation of exploration systems. Additionally, EDA measurements are expected to have important implications for the surface evolution of all airless bodies, including the Moon and asteroids, in the solar system.

Magnetically Compatible Brain Electrode Arrays Based on Single-Walled Carbon Nanotubes for Long-Term Implantation

Advancements in brain–machine interfaces and neurological treatments urgently require the development of improved brain electrodes applied for long-term implantation, where traditional and polymer options face challenges like size, tissue damage, and signal quality. Carbon nanotubes are emerging as a promising alternative, combining excellent electronic properties and biocompatibility, which ensure better neuron coupling and stable signal acquisition. In this study, a new flexible brain electrode array based on 99.99% purity of single-walled carbon nanotubes (SWCNTs) was developed, which has 30 um × 40 um size, about 5.1 kΩ impedance, and 14.01 dB signal-to-noise ratio (SNR). The long-term implantation experiment in vivo in mice shows the proposed brain electrode can maintain stable LFP signal acquisition over 12 weeks while still achieving an SNR of 3.52 dB. The histological analysis results show that SWCNT-based brain electrodes induced minimal tissue damage and showed significantly reduced glial cell responses compared to platinum wire electrodes. Long-term stability comes from SWCNT’s biocompatibility and chemical inertness, the electrode’s flexible and fine structure. Furthermore, the new brain electrode array can function effectively during 7-Tesla magnetic resonance imaging, enabling the collection of local field potential and even epileptic discharges during the magnetic scan. This study provides a comprehensive study of carbon nanotubes as invasive brain electrodes, providing a new path to address the challenge of long-term brain electrode implantation.

Research on Metal and Living Foreign Object Detection Method for Electric Vehicle Wireless Charging System

In the electric vehicle wireless power transmission system, the high-frequency alternating magnetic field between the transmitter and receiver can have a certain impact on the health of living organisms and may even lead to lesions. In addition, metal foreign objects in an alternating magnetic field can cause their own heating or even cause fires due to the eddy current effect, so foreign object detection is an essential function in the wireless power transmission system of electric vehicles. In order to prevent metals and living organisms from entering the charging area and causing harm to the charging system and living organisms, this paper proposes a method for detecting living organisms and metal foreign objects. Firstly, the equivalent circuits for the detection systems of the living organism foreign objects and metal foreign objects are established, respectively, and the working theory of the detection system is analyzed by deriving equations. Secondly, the comb capacitor simulation model was constructed, and the comb capacitor electrode spacing, wire thickness, and capacitor spacing were designed based on the scale factor γ to explore the effects of the height and bottom area of the living organism’s foreign object on the comb capacitor. We constructed a simulation model of the detection coil and designed the inner diameter D, the number of turns N, and the wire spacing S of the detection coil according to the scale factor β. An arrayed detection coil and comb capacitor combination mode is proposed to realize the function of the simultaneous detection of metal and living organism foreign objects, and a compensation capacitor is introduced to keep the detection system in a resonant state. Lastly, a platform for foreign object detection experiments was set up to detect metal screws and beef chunks compared to the detection area without foreign objects. Metal screws entering the detection area cause a 20% voltage drop in the detection circuit resistor, and beef chunks entering the detection area cause a 30% voltage drop in the detection circuit resistor, so the detection method is effective in detecting both metals and living organisms. The feasibility of the combined mode of arrayed detection coils and comb capacitors was verified.

Analyzing the dimensional errors in wire electric discharge machining of squeeze casted Al2024/Al2O3/W composite using cryogenic treated electrodes

Distinctive attributes of hybrid aluminum matrix composites enhance their industrial applications; however, reinforcement particulates complicate their machining, specifically when intricate profiles with high precision are involved due to their intended applications. This study investigates the dimensional accuracy of squeeze casted Al2024/Al2O3/W hybrid composite during wire electric discharge machining. A cone-shaped convoluted profile has been opted for machining to address the industrial needs, therefore, dimensional deviation in length, vertex angle and curvature radius of specimens have been assessed. The influence of cryogenic treatment of wire electrodes has been analyzed to control dimensional deviation in machining. Besides this, the influence of four machining variables including pulse duration, wire feed rate, wire runoff speed and wire tension on the dimensions deviations has also been investigated. The findings indicate that the pulse duration and wire tension notably influence the length error and curvature radius error. Additionally, the pulse duration and wire feed rate have been found to significantly impact the vertex angle error. The non-treated wire creates more significant craters and macro voids on the machined surface due to uneven sparking. In contrast, due to its enhanced electrical properties, the cryogenic-treated wire exhibits a comparatively refined microstructure on the machined surface, displaying fewer micro-voids and shallow craters. Comparative analysis shows that cryogenically treated wire offers 65.5 %, 35.3 % and 33.4 % reduction in length error, vertex angle error and curvature radius error than non-treated wire. The findings of this study can be helpful for the manufacturing industry for precision machining of intricate geometries.

A novel ventriculoperitoneal shunt flow sensor based on electrically induced spatial variation in cerebrospinal fluid charge density.

Introduction: Ventriculoperitoneal (VP) shunts divert cerebrospinal fluid (CSF) out of cerebral ventricles in patients with hydrocephalus or elevated intracranial pressure (ICP). Despite high failure rates, there exist limited clinically viable solutions for long-term and continuous outpatient monitoring of CSF flow rate through VP shunts. We present a novel, low-power method for sensing analog CSF flow rate through a VP shunt premised on induced spatial electrical charge variation. Methods: Two geometric variants of the proposed sensing mechanism were prototyped: linear wire (P1) and cylindrical (P2) electrodes. Normal saline was gravity-driven through P1 and a commercially available shunt system in series. True flow rates were measured using a high-precision analytical balance. Subsequently, artificial CSF was driven by a programmable syringe pump through P2. Flow rate prediction models were empirically derived and tested. Sensor response was also assessed during simulated obstruction trials. Finally, power consumption per flow measurement was measured. Results: P1 (17mm long) and P2 (22mm long) averaged 7.2% and 4.2% error, respectively, in flow rate measurement from 0.01 to 0.90mL/min. Response curves exhibited an appreciably flattened profile during obstruction trials compared to non-obstructed states. P2 consumed 37.5 µJoules per flow measurement. Conclusion: We propose a novel method for accurately sensing CSF flow rate through a VP shunt and validate this method at the benchtop with normal saline and artificial CSF over a board range of flows (0.01-0.90mL/min). The sensing element is highly power efficient, compact, insertable into existing shunt and valve assemblies, and does not alter CSF flow mechanics.

Experimental investigation of 3D taper profile machining of SS304 using WEDM

ABSTRACT Wire electrical discharge machining (WEDM) is an outstanding variety of EDM processes in which the tool is a wire electrode. The medical, electronics, tool, and die industries use stainless steel 304 (SS304). However, there are traditionally many complications that manufacturers face, while machining SS304. Also, the creation of 3D shapes using WEDM is challenging. Due to difficulties in normal machining and producing 3D profiles using conventional machining of SS304, this research aims to utilize the application of WEDM for creating complex shapes or products with top as square and bottom as rectangular shape to get a rectangular frustum. A ϕ 0.25 mm brass wire was used, and experiments were conducted as per L9 array. Further, the determination of the best process parameter (Ton, Toff, Voltage, current) combination for achieving the highest MRR, hardness, and minimal surface roughness (Ra) and kerf with analysis of machined surfaces using an SEM microstructure image was tried. The results indicated that MRR and Ra values varied from 7.05 to 47.29 mm3/min and 1.251 to 2.019 µm, respectively. Furthermore, the kerf ranged from 0.294 to 0.475 mm and hardness started at 164 to 233 HV. To optimize WEDM results Grey relational analysis (GRA) was utilized.

Present and Prospective Advancements in the Field of Deep Brain Stimulation Technology

Deep brain stimulation (DBS) in the neurosurgery domain allows for precise control of particular neural circuits. DBS has shown significant therapeutic effectiveness in the management of essential tremor, dystonia, and Parkinson's disease (PD). Moreover, ongoing research is investigating the potential of DBS as a therapy modality for several additional conditions characterized by aberrant circuitry, including depression and dementia. Over the last two decades, there has been a gradual improvement in DBS (Deep Brain Stimulation) devices, which today integrate an extension wire, pulse generator, and intracranial electrode. These components have been borrowed from the field of cardiology. The present paradigm of DBS is expected to undergo significant changes due to recent breakthroughs in technology and imaging, as well as a more comprehensive understanding of brain illnesses. Anticipated advancements in the tolerability and efficacy of DBS may be attributed to progress made in several areas, including battery and electrodes designing, stimulation systems, on-demand and closed-loop stimulation, including sensor technologies. This review provides a comprehensive examination of the historical and projected trajectory of DBS technology. By retrospectively examining the progress of DBS, we may enhance our understanding and recognition of our current position, as well as proactively forecast the next obstacles and prospects.

Robotizing double-electrode GMAW process through learning from human welders

Gas metal arc welding (GMAW) is the most robotized arc welding process and most widely used process for wire arc additive manufacturing (WAAM). Double-electrode GMAW (DE-GMAW) is its novel modification achieved by adding a second/bypass electrode. It provides the capability to freely adjust the base metal current (heat input) without changing the wire current (mass input). However, it must be robotized in order to be adaptive to manufacturing variations and constraints. Due to the complexity of the process, we propose learning from human welders through their attempts to adjust the bypass electrode in collaboration with the robotized GMAW. To generalize human success using a follower robot/surrogate, the distance between the wire and bypass electrode is proposed as the process state to quantify human observation and operation. As such, Inertial Measurement Unit (IMU) sensors are integrated to track the wire and bypass electrode operated by both the lead robot and the human welder. To interpret human adjustments per arc observation, a Convolutional Neural Network (CNN) is employed to process arc images and calculate the distance. The automatically obtained distance labels from IMU signals are used to train the CNN; however, they are noisy and inaccurate. Thus, the CNN is finely tuned through transfer learning using manually labeled distances. With accurately automatically calculated distances from the finely tuned CNN for all the data, the demonstrations from human welders are analyzed. The generalized knowledge is implemented by a robotic surrogate, substituting for the human welder to fully automate the DE-GMAW. Experiments demonstrated the superior performance of the fully robotized, and adaptively controlled, DE-GMAW process.

High-pressure plasma etching up to 9 atm toward uniform processing inside narrow grooves of high-precision X-ray crystal optics

We developed a new etching technique using plasma generated at high pressure up to 9 atm. Operating at 9-atm pressure with a 30-μm-diameter wire electrode, we demonstrated the generation of well-ordered plasma at a narrow gap of ∼10 μm between the electrode and workpiece, and realized a high spatial resolution of <40 μm during processing. This technique should allow for the processing of high-precision X-ray crystal optical devices with compact and complex structures, such as a micro channel-cut crystal monochromator with an extremely narrow (sub-100 μm width) groove for realization of Fourier-transform-limited X-ray lasers with high intensity.

High-precision finishing method for narrow-groove channel-cut crystal x-ray monochromator using plasma chemical vaporization machining with wire electrode.

A channel-cut crystal monochromator (CCM) is a popular and powerful device for producing monochromatic x-ray beams with extreme angular stability at a nano-radian level. Narrowing the groove width of CCMs has various benefits; for example, it is made possible to design more compact CCMs with an equivalent working energy range and to reduce the optical delay and the amount of beam shift, enhancing compatibility with various experimental techniques. An obstacle to the use of narrow-groove CCMs is the lack of a high-precision finishing method for the inner-wall reflecting surfaces, which imposes the distortion of x-ray wavefronts and spectral purity. We propose a new, damage-free surface-finishing method for silicon CCMs with a narrow groove of 1mm or less with a localized etching technique using plasma generated with a wire electrode of 50 µm diameter under atmospheric pressure. Repeating plasma-on and plasma-off periods with a pulsed power supply, we reduce the concentration of reaction products through self-diffusion during the plasma-off periods and minimize the redeposition of the products on the processed surface that deteriorates the surface roughness. Under optimized conditions, we processed a CCM with a groove width of 1.2mm, which has uniform reflection profiles and a nearly ideal reflectivity behavior for coherent monochromatic x rays.

Development of A Potentiometric Portable Extractor for Phosphate using Water Absorbent Materials and Cobalt Wire Electrodes

Soil phosphorus is an essential nutrient in the soil and is very necessary for plants, so measuring the content of elements or their derivatives in the soil is very necessary. This study aimed to develop a portable measuring instrument for phosphate based on the potentiometric principle using cobalt electrodes. The choice of absorbent material to support portable measuring instruments is based on water absorption and the potential response of the cobalt electrode when used with an absorbent. The phosphate electrode was made from cobalt wire and Ag/AgCl as a reference electrode. A comparison of analysis results was carried out between portable extraction potentiometric and conventional potentiometric methods. The results showed that polyvinyl alcohol (PVA) was the best absorbent. Using potentiometric measurements in a portable extractor prototype with PVA as an absorbent material offers promising prospects. The comparison of measurement results between the portable extractor and conventional potentiometric had 0.8039 as the correlation coefficient. Phosphate in conventional potentiometric was measured 1.2809 times higher than portable extraction potentiometric. The potentiometric slopes were -23.69 mv/decade and -26.63 mv/decade for the portable extractor potentiometric and the traditional potentiometric methods, respectively.

Experimental investigation of wire electrical discharge machining parameters on WE43 magnesium alloy

The influence of wire electrical discharge machining (WEDM) factors on the WE43 magnesium alloy is experimentally investigated in this work. Voltage, peak current, pulse-on time, and pulse-off time, are some of the factors taken into consideration in the study. The goal of the study is to understand how the output responses like material removal rate (MRR), surface roughness (SR), and development of recast layers are affected by the factors like voltage, peak current, pulse-on time and pulse-off time. The experimental set-up used a wire electrical discharge machine with a brass wire electrode and a workpiece made of the WE43 magnesium alloy. The L27 orthogonal array was used to alter the selected parameters through a series of experiments. The findings of the experimental investigation showed a strong link between the output responses and the electrical discharge machining (EDM) parameters. Peak current was discovered to have a direct correlation with the rate of material removal, with greater currents resulting in faster machining. SR and MRR were affected by pulse-on time and pulse-off time. Voltage had a direct impact on the development and thickness of the recast layer, with higher voltages favoring thinner recast layers.

Study on liquid dielectrophoresis based on double flexible electrodes simulating interdigitated pattern electrodes

Dielectrophoresis affects the surface wettability by applying a non-uniform electric field to dipoles inside dielectric liquid, achieving adjustable droplet contact angle and overcoming the saturation limitation of contact angle caused by the electrowettability effect. However, it is difficult to realize useful three-dimensional tunable optical devices because most of the driving electrodes need to be patterned. In this work, a model of double flexible electrodes simulating planar interdigitated pattern electrodes is proposed based on the dielectrophoresis. Double flexible electrodes, which are wrapped with an insulating dielectric layer and are not conductive to each other are arranged at close intervals and wound along the plane substrate to form a two-dimensional planar line wall. A hydrophobic layer is used to fill the gap and increase the initial contact angle. Ultimately, the “droplet-interdigitated planar line wall” dielectrophoresis driven-droplet model is formed after the dielectric droplets have been deposited on the line wall surface. Firstly, considering the influence of penetration depth and electrode gap area, Young’s equation is theoretically modified to adapt to this model. Then, the finite element algorithm simulation is used to used to comparatively analyze the potential distribution of this model and the planar interdigitated pattern electrode model. The field strength distributions of the electrodes with different wire diameters and insulating layer thickness values are analyzed. It can be found that with the increase of the diameter of the electrode wire and the thickness of the insulating layer, the morphology of the model changes from the tip electrode into the planar electrode, the surface field strength attenuates exponentially and the peak value decreases. This shows that the structure of this electrode in this model is superior to that of the planar electrode. After that, the contact angle of the model is measured experimentally in a range of 58°－90° under 0–250 &lt;i&gt;V&lt;/i&gt;&lt;sub&gt;rms&lt;/sub&gt; voltage, which is in line with the theoretical expectation. At the same time, neither obvious contact angle lag nor saturation is observed in the experiment. Finally, the new electrophoretic driving droplet model constructed in this paper transforms the dielectric electrophoretic driving mode from a two-dimensional planar electrode to a one-dimensional flexible linear electrode. Because of its flexibility and plasticity, it is convenient to form a three-dimensional cavity and can be applied to more complex device structures.

Zinc Oxide Nanowall Networks Growth on Indium Tin Oxide Substrates in an Oxygen Atmosphere and Magnetic Field via the Sparking Process

A zinc oxide nanowall (ZnO NW) network was grown on an indium tin oxide (ITO) surface using the sparking process at a breakdown voltage. This process involved four pairs of pure zinc wire electrodes in a flowing oxygen atmosphere, with a perpendicular magnetic field applied downward onto the ITO surface. It was observed that the cluster number density of ZnO NWs on the ITO surface decreased with an increasing number of coatings. The transmittances of the glass/ITO/ZnO NW network substrate increased again once the nanostructure was completely formed and achieved higher crystallinity.

A Flexible Sensor for Vancomycin Fabricated By Depositing Molecularly Imprinted Carbon Paste on a Wire

1. Introduction Vancomycin (VCM), an antibacterial drug, has a narrow effective blood concentration range, requiring therapeutic drug monitoring (TDM) to measure blood levels and optimize dosing regimens . Neonates, in particular, have large individual differences in the rate of drug metabolism, so strict TDM is necessary, but the dilemma is that the amount of blood drawn must be kept to a minimum. Therefore, we decided to develop a method of TDM without blood sampling by implanting a sensor that detects VCM under the skin. The sensor must be flexible enough not to damage the subcutaneous tissue. We have developed a sensor using a MIP carbon paste (MIP-CP) electrode, in which graphite particles with molecularly imprinted polymers are mixed with oil. Since higher mechanical strength is required for indwelling sensors, we fabricated MIP-carbon dough (MIP-CD) electrodes by mixing MIP with a thermosetting silicon resin prepolymer and thermosetting it. This was applied to a wire to develop a flexible wire-type sensor, and its performance was evaluated. 2. 2. experimental method 2-1. MIP graft polymerization /MIP-CD fabricationMethacrylic acid, ethylene glycol dimethacrylate, and allylamine carboxypropionic-3-ferrocene were graft copolymerized on the surface of graphite particles with fixed polymerization initiator in the presence of template VCM. Then, after washing and drying with sodium chloride solution and distilled water, the uncured MIP-CD was mixed with thermosetting silicone resin at a weight ratio of 7:3. Non-imprinted polymer (NIP)-CD, which was prepared by the same procedure without adding a template during synthesis, was also prepared for comparison.2-2. Fabrication of MIP-CD sensor Carbon ink was applied to a 20 mm tip of a 50 mm tin-plated copper wire, and uncured MIP-CD was applied on top. Then, silicon resin was applied for insulation to limit the effective area of the MIP-CD electrode, and both the insulation and MIP-CD were heat-cured in a dryer to fabricate the wire electrode shown in Fig. 1.2-3. measurement methodDifferential pulse voltammetry was performed on the MIP (or NIP)-CD sensor in phosphate buffer containing VCM or teicoplanin (TEIC), which has a similar structure, and the relationship between current and concentration was plotted. 3. Results and Discussion A comparison of the sensitivity of MIP-CD and NIP-CD electrodes to VCM is shown in Fig. 2: the current at MIP-CD increased linearly with increasing VCM concentration, while that at NIP-CD was insensitive. This result indicates that the current at the MIP-CD electrode reflects the specific binding of VCM to the imprinted binding site. As shown in Fig. 3, the MIP-CD electrode was not sensitive to TEIC and showed high selectivity. Conclusion The electrode with MIP-CD fixed on a wire is strong and flexible, yet has a specific response to VCM, and is expected to be used as an indwelling subcutaneous sensor.*This work was supported by the Bridging Research Program of the Japan Agency for Medical Research and Development (Keio University Center). Figure 1

The Power of Reference Electrodes in AEM Electrolysis

The use of reference electrodes is a powerful diagnostic tool to determine the overpotentials associated with oxygen and hydrogen evolution reaction. Yet, the use of reference electrodes in flow cells is still uncommon and provides several challenges especially related to the stability of the potential of the reference electrode. This study investigates the use of a reference electrode in a well-performing iridium-free AEM flow cell with a cell potential of <1.8 V @ 1.5 A cm-2. The reference electrode consists of electrically insulating foil with two platinum wire electrodes on one side as shown in Figure 1(left). A small micro-current is passed through the platinum wires to maintain hydrogen coverage on the reference electrode to establish equilibrium cell potential. The use of the reference electrode shows that the platinum-ruthenium cathode performs particularly well with an overpotential of <0.1 V @ 0.2 A cm-2.The reference electrode also is useful for the study of cell degradation. One of the major challenges of coupling electrolyzer directly to renewables are reverse currents flowing after shutdown in alkaline and AEM electrolyzers [1]. In this study, polarities were reversed to simulate these reverse currents. This lead to a significant increase in cell potential. It is clearly evident from Figure 1(right) that the cathode overpotentials increased significantly after this reverse current application, thereby indicating that the platinum-ruthenium cathode is vulnerable to reverse currents.[1]Ashraf Haleem et al, Effects of operation and shutdown parameters and electrode materials on the reverse current phenomenon in alkaline water analyzers, Journal of Power Sources, Volume 535, 2022, 231454, ISSN 0378-7753, https://doi.org/10.1016/j.jpowsour.2022.231454 Figure 1

Simulation of radon detection efficiency with small pulse ionization chamber based on Geant4

Radon measurement is crucial in assessing the damage to the human body caused by natural radiation. Pulsed ionization chambers are effective for real-time radon measurement and have widespread applications in other radiation techniques. However, due to practical constraints such as limited space and portability concerns, it becomes imperative to consider not only the detection efficiency but also their ease of transportation. This work utilizes the Geant4 Monte Carlo simulation toolkit to characterize the detection models of small cylindrical and flat plate-type pulsed ionization chambers, and carry out a simulation study to analyze the three crucial factors that influence detection efficiency, including the geometry of the chamber, electrode size, and operating temperature. The results indicate that the cylindrical pulse ionization chamber, with a length of 8 cm and radius of 2 cm, has the best detection efficiency and portability in terms of geometric dimensions, achieving a detection efficiency of (58 ± 4)%. Meanwhile, the flat plate pulse ionization chamber, with dimensions of 7 cm in length and 3 cm in width, achieves the best detection efficiency and portability, with a detection efficiency of (54 ± 3)%. In terms of electrode wire size, the cylindrical ionization chamber electrode wire with a length of 7 cm and a radius of 2.5 mm was optimal with a detection efficiency of (59 ± 4)%. In terms of operating temperature, the detection efficiency of the flat-plate pulsed ionization chamber was the highest at 30 °C, which was (58 ± 4)%, and that of the cylindrical pulsed ionization chamber was the highest at 20 °C, which was (63 ± 4)%. By analyzing the influencing factors of the detection efficiency of the pulsed ionization chamber, it has a certain reference value and guiding significance for the research and design of small pulsed ionization chamber detectors for radon measuring instruments.

Enhancing Cutting Rates in Multi-Channel HSWEDM of Metal Materials with a Novel Decoupling Circuit.

Multi-channel high-speed wire electrical discharge machining (HSWEDM) has shown great potential in enhancing the cutting rate of metal workpieces. However, the mechanism of multi-channel discharges in this technique remains unclear. In this paper, the equivalent circuit and processing model of the multi-channel HSWEDM were developed to investigate the discharge characteristics. It was found that the equipotential between electrodes is the primary factor causing electrical signal coupling between channels, hindering the achievement of synchronous discharge. To address this issue, a novel power supply with a decoupling circuit was devised. By utilizing the combined effect of electrode wire resistance and current limiting resistance (Rc), a potential difference was induced between electrodes in different channels, enabling electrical signal decoupling and facilitating synchronous discharge. The impact of Rc on synchronous discharge was examined, revealing that a reduction in Rc can increase the gap voltage of non-breakdown channels, thereby enhancing the discharge ratio. Finally, cutting rate experiments were conducted. When the new power supply was used for electrical signal decoupling, the cutting rates of multi-channel WEDM were significantly improved. Compared to single-channel HSWEDM, the cutting rates of two-channel and four-channel HSWEDM are enhanced by 84.06% and 247.83%, respectively.