Search Results (243)

Obtaining stable ECG signals under both static and dynamic conditions, while ensuring comfortable wear, is a prerequisite for fabric-electrode applications. It is necessary to study the wearing pressure of fabric electrodes as well as their organizational structure. In this study, fabric electrodes with different organizational structures (plain weave, twill weave, and satin weave) were prepared using silver-plated nylon conductive yarns as weft yarns and polyester yarns as warp yarns. The electrical characteristics of these structures of fabric electrodes were analyzed under different wearing pressures (2 kPa, 3 kPa, 4 kPa, and 5 kPa), and their effects on the quality of static and dynamic ECG signals acquired from human body were examined. The results showed that the contact impedance of the twill and satin weave structured electrodes with the skin was smaller and more stable than that of the plain weave structured electrodes. Furthermore, when a wearing pressure of 3–4 kPa was applied to the satin-structured electrodes, they not only provided satisfactory comfort but also collected stable static and dynamic ECG signals during daily exercise. These results can provide a reference for the application of fabric electrodes in ECG monitoring devices and an important basis for the design of intelligent ECG clothing. Full article

This article focuses on the possibilities of increasing the service life of tools for crushing unwanted growths. One way to increase their service life is to increase the hardness and resistance to abrasive wear of exposed surfaces of the tool, which are their face and back. At the same time, however, care must be taken to ensure that the shape and weight of the tool is not altered after the additive has been hardfaced on. Thus, the tool was first modified by removing the material by milling from the face and back. Subsequently, two surfacing materials, namely UTP 690 and OK WearTrode 55, were chosen and hardfaced by welding onto the pre-prepared surfaces. After hardfacing by welding, the tools were ground to their original shape and their weight was measured. Subsequently, the tool was sawn, and specimens were created for Rockwell hardness evaluation, material microstructure and for abrasive wear resistance testing as per ASTM G133-95. The OK WearTrode 55 electrode is a hardfacing electrode that produces weld metal with a high-volume fraction of fine carbides in a martensitic matrix. Better results were achieved by the UTP 690 hardfacing material. The hardness was 3.1 times higher compared to the base tool material 16MnCr5 and 1.2 times higher than the OK WearTrode 55 material. The abrasive wear resistance was 2.76 times higher compared to 16MnCr5, and 1.14 times higher compared to the OK WearTrode 55 material. The choice of a suitable pre-treatment for the tool and the selection and application of such additional material, which with its complex properties better resists the effects of the working environment, is a prerequisite for increasing the service life of tools working in forestry. Full article

Currently, the electroencephalogram (EEG) cap is limited to a finite number of sizes based on head circumference, lacking the mechanical flexibility to accommodate the full range of skull dimensions. This reliance on head circumference data alone often results in a poor fit between the EEG cap and the user’s head shape. To address these limitations, we have developed a four-dimensional (4D) adjustable EEG cap. This cap features an adjustable mechanism that covers the entire cranial area in four dimensions, allowing it to fit the head shapes of nearly all adults. The system is compatible with 64 channels or lower electrode counts. We conducted a study with numerous volunteers to compare the performance characteristics of the 4D caps with the commercial (COML) caps in terms of contact pressure, preparation time, wearing impedance, and performance in brain–computer interface (BCI) applications. The 4D cap demonstrated the ability to adapt to various head shapes more quickly, reduce impedance during testing, and enhance measurement accuracy, signal-to-noise ratio (SNR), and comfort. These improvements suggest its potential for broader application in both laboratory settings and daily life. Full article

The mental fatigue of crane operators can pose a serious threat to construction safety. To enhance the safety of crane operations on construction sites, this study proposes a rotary switch semi-dry electrode for detecting the mental fatigue of crane operators. This rotary switch semi-dry electrode overcomes the problems of the large impedance value of traditional dry electrodes, the cumbersome wet electrode operation, and the uncontrollable outflow of conductive liquid from traditional semi-dry electrodes. By designing a rotary switch structure inside the electrode, it allows the electrode to be turned on and used in motion, which greatly improves the efficiency of using the conductive fluid and prolongs the electrode’s use time. A conductive sponge was used at the electrode’s contact end with the skin, improving comfort and making it suitable for long-term wear. In addition, in this study, the multifractal detrend fluctuation analysis (MF-DFA) method was used to detect the mental fatigue state of crane operators. The results indicate that the MF-DFA is more responsive to the tiredness traits of individuals than conventional fatigue detection methods. The proposed rotary switch semi-dry electrode can quickly and accurately detect the mental fatigue of crane operators, provide support for timely warning or intervention, and effectively reduce the risk of accidents at construction sites, enhancing construction safety and efficiency. Full article

Nickel (Ni) ultrathin films exhibit phase-dependent electrical, magnetic, and optical characteristics that are significantly influenced by deposition methods. However, these films are inherently prone to rapid oxidation, with the oxidation rate dependent on substrate, temperature, and deposition parameters. The focus of this research is to investigate the temporal oxidation of RF-sputtered Ni ultrathin films on Corning glass under ambient atmospheric conditions and its impact on their structural, surface, and optical characteristics. Controlled film thicknesses were achieved through precise manipulation of deposition parameters, enabling the analysis of oxidation-induced modifications. Atomic force microscopy (AFM) revealed that films with high structural integrity and surface uniformity are exhibiting roughness values (Rq) from 0.679 to 4.379 nm of corresponding thicknesses ranging from 4 to 85 nm. Scanning electron microscopy (SEM) validated the formation of Ni grains interspersed with NiO phases, facilitating SPR-like effects. UV-visible spectroscopy is demonstrating thickness-dependent spectral (plasmonic peak) shifts. Finite Difference Time Domain (FDTD) simulations corroborate the observed thickness-dependent optical absorbance and the resultant shifts in the absorbance-induced plasmonic peak position and bandgap. Increased NiO presence primarily drives the enhancement of electromagnetic (EM) field localization and the direct impact on power absorption efficiency, which are modulated by the tunability of the plasmonic peak position. Our work demonstrates that controlled fabrication conditions and optimal film thickness selection allow for accurate manipulation of the Ni oxidation process, significantly altering their optical properties. This enables the tailoring of these Ni films for applications in transparent conductive electrodes (TCEs), magneto-optic (MO) devices, spintronics, wear-resistant coatings, microelectronics, and photonics. Full article

This study investigates the tribo-mechanical properties of a modified Cu-Cr-Zr alloy with nickel addition, aimed at enhancing its suitability as a resistance spot welding (RSW) electrode material. Two alloy compositions, designated as Sample A (Cu-0.871%Cr-0.156%Zr) and Sample B (modified with 8.94% Ni), were prepared. Microstructural examination revealed a coarse, mixed equiaxed–columnar grain structure in Sample A, while Sample B exhibited a refined dendritic morphology of about 50 μm PDAS, due to nickel-induced solute partitioning, improving microhardness from 72.763 HV to 83.981 HV. The wear behavior was evaluated using a pin-on-disc tribometer with a full factorial design, assessing the effects of rotational speed, load, and time on mass loss and surface roughness. Sample A exhibited increased mass loss and roughness with higher loads and speeds, indicating severe wear. In contrast, Sample B showed reduced mass loss and roughness at higher loads, suggesting a polishing effect from plastic deformation. Design of experiments analysis identified load as the dominant factor for mass loss in Sample A, with speed primarily affecting roughness, while in Sample B, load negatively influenced both responses, with speed–time interactions being significant. These findings highlight the nickel-modified alloy’s superior wear resistance and hardness, making it a promising candidate for RSW electrodes in high-production environments. Full article

Silicon is the most commonly used material in the electronic industries due to its unique properties, which also make it very difficult to machine using conventional machining. Electrical discharge machining (EDM) is a non-traditional process that is gaining popularity for machining silicon, although a slower machining rate is one of its limitations. This study investigates two electrode design strategies to enhance the efficiency of EDM by improving the material removal rates, reducing tool wear, and refining the quality of machined features. The first approach involves using graphite electrodes in various array configurations (1 × 4 to 6 × 4) and leg heights (0.2″ and 0.3″). The second approach employs hollow electrodes with differing wall thicknesses (0.04″, 0.08″, and 0.12″). The effects of these variables on performance were evaluated by maintaining constant EDM parameters. The results indicate that increasing the number of electrode legs improves the flushing conditions, resulting in shorter machining times. Meanwhile, the shorter electrode height outperforms the taller electrode, providing a higher machining speed. The thinnest wall thickness for hollow electrodes yielded the best performance due to the increased energy distribution. Both electrode design methodologies can be used for the mass fabrication of features with targeted profiles on silicon using the die-sinking EDM process. Full article

Wire electrochemical discharge machining (WECDM) integrates the effectiveness of electrical discharge machining (EDM) with the superior quality of electrochemical machining (ECM), leading to enhanced machining efficiency, excellent surface finish, and significant potential for advancement. However, previous research has mainly focused on the processing of non-metallic materials, with little research in the field of the microfabrication of thick metal materials. The wire electrochemical discharge machining process with large aspect ratios is more complex. Accordingly, a unidirectional traveling wire electrochemical discharge micromachining (UWECDMM) method using a glycol-based electrolyte was proposed. The method employs a glycol solution with low conductivity and a neutral salt, facilitating enhanced mass transfer efficiency through a unidirectional traveling wire, and enabling the realization of high-efficiency, high-precision, and recast-free processing. The phenomenon of discharge in UWECDMM was observed in real-time with a high-speed camera, while the voltage and current waveforms throughout the machining process were carefully analyzed. It was found that electrolysis and discharge alternate. Experiments were conducted to investigate the wire traveling pattern, the recast layer, and the wear of the wire electrode. It was found that due to the small energy of a single discharge, the wear of wire electrodes is minimal after multiple uses and can be reused. Under optimal parameters, a machined surface without a recast layer can be obtained. In the final stages, a standard structure was machined on plates of 10 mm thickness made of pure nickel and 304 stainless steel, using a tungsten wire measuring 30 μm in diameter. The feed rate achieved was 1 μm/s, the surface roughness (Ra) measured 0.06 μm, and the absence of a recast layer confirmed the method’s sustainability and quality traits, indicating significant potential in microfabrication. Full article

Die-sinking Electrical Discharge Machining (EDM) is a manufacturing process for fabricating complex geometries in challenging applications. However, its energy-intensive nature and complex parameter interactions pose challenges in balancing productivity, sustainability, and electrode wear. This study presents a comprehensive analysis of energy consumption and electrode degradation in EDM. Utilizing an advanced experimental setup with real-time energy monitoring, this study investigated the trade-off between machining parameters, energy efficiency, and electrode wear. The study employed a simple and standardized electrode geometry and varied EDM parameters, such as discharge current and pulse duration. The obtained results clearly demonstrated that optimizing EDM machining parameters, particularly discharge current, significantly influenced machining efficiency and electrode wear. Specifically, employing high-current settings of 140 A substantially reduced the total machining time from approximately 33 h (at conservative settings of 40 A) down to around 3.5 h, achieving nearly a tenfold improvement. Moreover, it also led to a reduction in specific energy consumption (SEC), decreasing from 0.81 Wh/mm³ at the low current (40 A) to 0.19 Wh/mm³ at the higher current (140 A), underscoring a definitive inverse relationship between discharge current and energy consumption. The study outcomes provide practical guidelines for enhancing the operational efficiency and sustainability of EDM in advanced manufacturing sectors. Full article

Efficient coal grinding is a crucial aspect of the energy and mining industries. However, traditional grinding methods are known to be energy-intensive and cause significant wear on equipment as well as negative environmental impacts due to the release of small particles that can harm air quality and affect human health. In response to these challenges, we are conducting research to develop an electric pulse device for coal grinding. This device will use high-voltage discharges in a liquid medium to create shock waves that selectively destroy coal particles while minimizing mechanical damage. The electric pulse installation consisted of a control unit (for monitoring the operating modes of the installation), a generator (for converting the AC input voltage into DC output voltage), a capacitor (for energy storage), a protection system (for shutting down the installation in cases when a voltage exceeding the set safe operating discharge voltage occurs on the capacitor), a spark gap (forming a gap consisting of two conductive hemispherical electrodes separated by an air gap, designed to form an electric spark between conductors), and an electric pulse grinding device. The input material for each experiment had consistent parameters: the coal particles were diameter 8–10 mm and weighed 400 g. Coal was processed using the electric pulse method with various voltage values, numbers of pulses, capacitor capacities, and pulse frequencies. The yield of the final product depended on these parameters, and effective settings for producing coal powder were identified. The research results demonstrate that a flat metal mesh plate is effective as the negative electrode in the electric pulse grinding device. Full article

This work demonstrates the possibility of creating effective composite coatings with a complex structure and phase composition on carbon steel C45 via electrospark deposition (ESD) with multicomponent electrodes with a bonding mass composition of Co-Ni-Cr-B-Si semi-self-fluxing alloys and superhard compounds WC, B₄C and TiB₂. The variation in the roughness, thickness, composition, structure, microhardness and wear at the friction of the coatings as a function of the ratios between the bonding mass and the high-hardness components in the composition of the electrode and of the pulse energy for ESD has been studied. It has been established that with a content of the bonding mass in the electrode of 25–35%, coatings with improved adhesion and simultaneously higher hardness and toughness are obtained. Suitable electrode compositions and optimal pulse energy have been defined, which provide dense and uniform coatings with an increased amount of crystalline-amorphous structures, as well as intermetallic and wear-resistant phases, with thickness, roughness and microhardness that can be changed by the ESD modes in the ranges of δ = 8–65 µm, Ra = 1.5–7 µm, and HV 8.5–15.0 GPa, respectively, and minimal wear of the coated surfaces that is up to 5 times lower than that of the substrate and up to 1.5 times lower than that obtained with conventional WC-Co electrodes. Full article

In the process of micro-EDM, tool electrode wear is inevitable, especially for complex three-dimensional cavities or microgroove structures. Tool electrode wear accumulates during machining, which will finally affect machining accuracy and machining quality. It is necessary to reduce electrode wear and compensate it through micro-EDM. Therefore, based on an established L27 orthogonal experiment, this paper uses the grey relational analysis (GRA) method to realize multi-objective optimization of machining time and electrode wear, so as to achieve the shortest machining time and the minimum electrode wear during machining under the optimal machining parameter combination. Then, the orthogonal experiment results are used as dataset of artificial neural networks (ANNs), and an ANN prediction model is established. Combined with image processing technology, the bottom profile of the machined microgroove is extracted and then an electrode axial wear compensation equation is fitted, and a fixed-length nonlinear compensation method for electrode axial wear is proposed. Finally, the GRA optimal experiment shows that machining time, electrode axial wear and radial wear are reduced by 13.89%, 3.31%, and 10.80%, respectively, compared with the H17 orthogonal experiment with the largest grey relational grade. For the study of electrode axial wear compensation methods, the consistency of the depth and width of the machined microgroove structure with compensation is significantly better than that of the microgroove structure without compensation. This result shows that the proposed fixed-length nonlinear compensation method can effectively compensate electrode axial wear in micro-EDM and improve machining quality to a certain extent. Full article

The widespread adoption of electric vehicles (EVs) has introduced new challenges in drivetrain lubrication, particularly concerning electrical corrosion, frictional wear, and hydrogen embrittlement. While polyalphaolefin (PAO)-based lubricants are commonly used, they struggle under high-speed and high-torque conditions. In contrast, polyphenyl ether (PPE)-based lubricants offer superior wear resistance and effectively suppress hydrogen generation, making them promising for EV applications. This study examines the effects of current direction and magnitude on tribofilm formation and frictional behavior in a PPE-lubricated environment. The results show that PPE exhibits unique tribofilm adhesion characteristics influenced by electrical conditions, unlike PAO. Surface analysis reveals that the tribofilm mainly consists of amorphous carbon, and friction under an electrical bias induces PPE oxidation, with oxidation products forming more readily at the positive electrode. Tribofilm formation correlated with increased friction and wear, particularly under currents of 10 mA or higher. Although PPE is more sensitive to electrical influences than PAO, it exhibits excellent wear resistance and maintains a low coefficient of friction even under electrification. This suggests that PPE could be suitable for lubrication in electrical environments and may serve as a promising lubricant for EV drive systems and similar applications. Full article

Hand gesture recognition is a prominent topic in the recent literature, with surface ElectroMyoGraphy (sEMG) recognized as a key method for wearable Human–Machine Interfaces (HMIs). However, sensor placement still significantly impacts systems performance. This study addresses sensor displacement by introducing a fast and low-impact orientation correction algorithm for sEMG-based HMI armbands. The algorithm includes a calibration phase to estimate armband orientation and real-time data correction, requiring only two distinct hand gestures in terms of sEMG activation. This ensures hardware and database independence and eliminates the need for model retraining, as data correction occurs prior to classification or prediction. The algorithm was implemented in a hand gesture HMI system featuring a custom seven-channel sEMG armband with an Artificial Neural Network (ANN) capable of recognizing nine gestures. Validation demonstrated its effectiveness, achieving $93.36$% average prediction accuracy with arbitrary armband wearing orientation. The algorithm also has minimal impact on power consumption and latency, requiring just an additional 500 μW and introducing a latency increase of 408 μs. These results highlight the algorithm’s efficacy, general applicability, and efficiency, presenting it as a promising solution to the electrode-shift issue in sEMG-based HMI applications. Full article

The increasing demand for sustainable and cost-effective manufacturing solutions has led to the development of innovative approaches to enhance the durability and reliability of cutting tools. This study presents a novel method for manufacturing shearing tools utilizing interchangeable modular elements loaded by deposition welding with covered electrodes. Using Weibull distribution modeling, a comparative reliability analysis between conventionally manufactured shear tools and the proposed modular design demonstrates a significant increase in the mean time to failure (MTTF). The least squares method (LSM) estimation was used in order to determine the shearing tools’ lifetime, expressed by reliability indices. Experimental results confirm that the modular tools achieve more than double the lifetime of traditional counterparts, with improved resistance to wear and mechanical stress. These findings highlight the potential for widespread industrial application, optimizing tool performance and sustainability in manufacturing processes. Full article