Search Results (66)

Harmonics are a common phenomenon widely present in power systems. The presence of harmonics not only increases the energy consumption of equipment but also poses hidden risks to the safety and stealth performance of large ships. Thus, there is an urgent need for a detection method for the harmonic characteristics of time series. We propose a novel harmonic feature estimation method, termed Harmonic Aggregation Entropy (HaAgEn), which effectively discriminates against background noise. The method is based on bispectrum analysis; utilizing the distribution characteristics of harmonic signals in the bispectrum matrix, a new Diagonal Bi-directional Integral Bispectrum (DBIB) method is employed to effectively extract harmonic features within the bispectrum matrix. This approach addresses the issues associated with traditional time–frequency analysis methods, such as the large computational burden and lack of specificity in feature extraction. The integration results, $I_x$ and $I_y$, of DBIB on different frequency axes are calculated using cross-entropy to derive HaAgEn. It is verified that HaAgEn is significantly more sensitive to harmonic components in the signal compared to other types of entropy, thereby better addressing harmonic detection issues and reducing feature redundancy. The detection accuracy of harmonic components in the shaft-rate electromagnetic field signal, as evidenced by sea trial data, reaches 96.8%, which is significantly higher than that of other detection methods. This provides a novel technical approach for addressing the issue of harmonic detection in industrial applications. Full article

Despite ongoing concerns about electromagnetic interference affecting cardiac implantable electronic devices (CIEDs) in the electrical industry workplaces, no study has experimentally assessed induced voltages in CIEDs under exposure to power-frequency magnetic fields. This study addresses this gap by quantifying such interference using a dedicated experimental setup to reproduce high intensity magnetic fields and to measure voltages induced on CIEDs under exposure. A thorough analysis was carried out in comparison with formula-based and simulation approaches applied in previous studies. The induced voltages on CIEDs were measured across varying configurations, including sensing mode, implantation method, exposure frequency, and magnetic field orientation. Our findings reveal the induced voltage levels under exposure from a statistical perspective and highlight correlations between susceptibility and the impact factors, with unipolar configurations and left pectoral implants exhibiting the highest susceptibility. This work provides insights into electromagnetic interference risks for CIED carriers and supports the development of individual protection strategies to enhance occupational safety. Full article

To address the issue of uneven temperature distribution during the tire vulcanization process based on electromagnetic heating, this study focuses on the hot plate of a tire vulcanizing machine. An octagonal hot plate with dimensions of 1380 mm × 1380 mm × 60 mm was adopted, and temperature sensors were installed to monitor temperature changes in real time. Through electromagnetic simulation, the effects of current intensity, frequency, and coil-to-hot-plate distance on temperature uniformity were studied. The simulation results show that the temperature difference increases with current intensity and current frequency, while the temperature difference decreases with the increase in coil-to-hot-plate distance. To minimize the temperature gradient, the coil layout was structurally optimized based on the geometric features of the hot plate to improve magnetic field distribution. Several coil arrangements were designed and compared, including uniform, dual-ring, multi-ring, and the newly proposed flower-shaped configuration. It shows that the multi-ring circular coil has the best uniformity when heating a circular hot plate, and the flower-shaped coil has best temperature uniformity when heating an octagonal hot plate. Experimental validation using an industrial-scale prototype confirmed that the optimized design reduced temperature variation to within ±2 degrees Celsius. This work contributes a practical and geometrically informed coil design strategy for improving the temperature uniformity and energy efficiency of electromagnetic heating systems in industrial tire vulcanization. Full article

Low-frequency electromagnetic fields, induced by alternating current (AC)-based equipment such as transformers, are known to influence the physicochemical properties and function of enzymes, including their catalytic activity. Herein, we have investigated how incubation near a 50 Hz AC autotransformer influences the physicochemical properties of horseradish peroxidase (HRP), by atomic force microscopy (AFM) and spectrophotometry. We found that a half-hour-long incubation of the enzyme above the coil of a loaded autotransformer promoted the adsorption of the monomeric form of HRP on mica, enhancing the number of adsorbed enzyme particles by two orders of magnitude in comparison with the control sample. Most interestingly, the incubation of HRP above the switched-off transformer, which was unplugged from the mains power supply, for the same period of time was also found to cause a disaggregation of the enzyme. Notably, an increase in the activity of HRP against ABTS was observed in both cases. We hope that the interesting effects reported will emphasize the importance of consideration of the influence of low-frequency electromagnetic fields on enzymes in the design of laboratory and industrial equipment intended for operation with enzyme systems. The effects revealed in our study indicate the importance of proper shielding of AC-based transformers in order to avoid the undesirable influence of low-frequency electromagnetic fields induced by these transformers on humans. Full article

The dielectric constant, or permittivity, is a fundamental property that characterizes a material’s electromagnetic behavior, crucial for diverse applications in agriculture, healthcare, industry, and scientific research. In microwave engineering, accurate permittivity measurement is essential for advancements in fields such as biomedicine, aerospace, and microwave chemistry. However, conventional waveguide resonator methods face challenges when measuring high-loss materials, often leading to reduced accuracy and increased cost. This paper introduces a lightweight, compact system for dielectric constant measurement using a negative-resistance voltage-controlled oscillator (VCO) integrated within a frequency synthesizer. The proposed system employs phase response variations of a planar sensor embedded in the VCO’s gate network to detect changes in oscillation frequency, enabling precise measurement of high-loss materials. The experimental validation demonstrates the system’s capability to accurately measure dielectric constants of lossy organic liquids, with applications in distinguishing liquid mixtures. The contributions include the design of a resonant-network-attached oscillator, comprehensive sensor performance simulations, and successful characterization of organic liquid mixtures, showcasing the potential of this approach for practical dielectric property measurements. Full article

Radiation detection uses semiconductor materials to convert high-energy photons into charge (direct detection) or low-energy photons (indirect detection), and it has a wide range of applications in nuclear physics, medical imaging, astronomical detection, homeland security, and other fields. Metal halide perovskites have the advantages of high frequency number, high carrier mobility, high defect tolerance, low defect density, adjustable band gap, and fast light response, and they have wide application prospects in the field of radiation detection. However, the research is still in its infancy stage, and it is far from meeting the requirements of industrial application. This paper focuses on the advantages of metal halide perovskite single-crystal materials in both semiconductors-based direct conversion detection and scintillator-based indirect detection as well as the latest progress in this promising field. This paper not only introduces the latest application of lead halide perovskite monocrystalline materials in high-energy electromagnetic radiation detection (X-ray and γ-rays), but it also introduces the latest development of α-particle/β-particle/neutron detection. Finally, this paper points out the challenges and future prospects of metal halide perovskite single-crystal materials in radiation detection. Full article

Extremely low-frequency electromagnetic fields (ELF-EMFs) are ubiquitous in industrialized environments due to the continuous use of electrical devices. Our previous studies demonstrated that ELF-EMFs affect muscle cells by modulating oxidative stress and enhancing myogenesis. This pilot study investigated these effects on the skeletal muscles of sedentary adult mice, assessing physiological responses to ELF-EMF exposure and potential modulation by antioxidant supplementation. Male C57BL/6 mice were exposed to ELF-EMFs (0.1 or 1.0 mT) for 1 h/day for up to 5 weeks and fed a standard diet without or with N-acetyl-cysteine (NAC). The results showed transient increases in muscle strength (after 2 weeks of exposure at 1.0 mT), potentially linked to muscle fiber recruitment and activation, revealed by higher PAX7 and myosin heavy chain (MyH) expression levels. After ELF-EMF exposure, oxidative status assessment revealed transient increases in the expression levels of SOD1 and catalase enzymes, in total antioxidant capacity, and in protein carbonyl levels, markers of oxidative damage. These effects were partially reduced by NAC. In conclusion, ELF-EMF exposure affects skeletal muscle physiology and NAC supplementation partially mitigates these effects, highlighting the complex interactions between ELF-EMFs and antioxidant pathways in vivo. Further investigations on ELF-EMFs as a therapeutic modality for muscle health are necessary. Full article

The research on MEMS wireless sensing technology adapted to strong power frequency electromagnetic field environments is of great significance to our energy security, economic society, and even national security. Here, we propose a subwavelength cross-meandering resonator (0.49λ₀ × 0.49λ₀) to simultaneously achieve power frequency electromagnetic field shielding and wireless communication signal transmission. The element size of the resonator is only λ₀/11, which is much smaller than that of previous works. In the resonator, a resonance mode with the significant near-field enhancement effect (about 180 times that at f = 1 GHz) is supported. Based on the self-made shielding box experimental setup, the measured shielding effectiveness of the resonator sample can reach more than 33 dB. Moreover, by integrating the cross-meandering resonator with the MEMS sensor, a wireless communication signal can be successfully transmitted. A dual-function cross-meandering resonator integrated with sensors may find potential applications in many military and civilian industries associated with strong power frequency electromagnetic fields. Full article

Wireless power transfer (WPT) systems have ushered in a new era for wearable and implantable technologies, introducing opportunities for enhanced device functionality. A pivotal aspect in improving these devices is the optimization of electromagnetic transmission. This paper presents several solutions to improve electromagnetic transmission to an implantable/wearable device. Several scatterers are considered to mimic objects that can be easily worn by a patient, such as necklaces and bracelets, or easily integrated into textile fabric. An analytical method is employed to address the scattering by cylindrical objects above a biological tissue, modeled as a multilayer. Expansions into cylindrical waves, also represented through plane-wave spectra, are used to express the scattered fields in each medium. Numerical results for both the case of conducting and of dielectric cylindrical scatterers are presented at a frequency of the Industrial, Scientific and Medical band ($f=2.45$ GHz), showing possible configurations of worn objects for electromagnetic field intensification. Full article

Electrodeless Low-Frequency (LF)/Radio-Frequency (RF) plasma sources often suffer from low power coupling efficiencies due to the lack of overlapping field with the dynamic plasma load. However, the power supplies for these plasma sources typically have very high power efficiencies (>90%) and are more cost-effective compared to microwave sources. If the coupling efficiency to the plasma can be increased, these plasma sources offer a competitive technology for the sustainable electrification of the chemical industry. This work experimentally investigates five power coupling methods, applied to toroidal CO₂ plasmas in a quartz vessel. The research was based on similar ferrite coupling as used in energy-efficient plasma lamps. The higher resistance of the CO₂ plasma decreased the power coupling from 90% (for mercury-vapor plasma) to 66% at 1 mbar. High coupling efficiencies in LF/RF powered discharges can be achieved in two manners: either the inductance of the transformer cores can be increased, or the electromagnetic wave frequency can be increased. Furthermore, additional ferrite cores in parallel with the primary coils can be used to increase the impedance transformation. An experiment with six ferrite cores with a single primary winding in parallel, at a frequency of about 10 MHz and a power of 1 kW, showed that this frequency has a detrimental effect on the magnetic permeability and the losses in the ferrite result in a decrease of coupling to 33% at 1.5 mbar. At a frequency of 66 kHz with a nanocrystalline soft magnetic material core, a coupling of 89% was achieved in 1.5 mbar plasma for a power of 3.1 kW. This configuration exhibits decreasing coupling efficiencies at higher pressures since the plasma impedance increases, which again limits the coupling of the transformer due to a lack of inductance. The investigation of alternative coreless coil plasma configurations resulted in coupling efficiencies up to 89% decreasing to 50% at 102 mbar for a toroidal plasma enclosed by toroidally spiraling coils. Full article

In this study, a circulating water experimental system was constructed to investigate the scale inhibition, scale removal, corrosion inhibition, and disinfection effects of industrial circulating water under the combined action of electromagnetic and electrochemical fields. The influence of these effects on water quality parameters and their scale inhibition and corrosion inhibition effects on hanging plate experiments were examined. Qualitative and quantitative analyses of scale samples were conducted using XRD (X-ray diffraction) and SEM (scanning electron microscopy), along with the evaluation of changes in water quality parameters (such as conductivity, hardness, Chemical Oxygen Demand (COD), turbidity, iron ions, and chloride ions) before and after the experiments. The results showed that after 360 h of circulation experiment, at a water temperature of 30 °C, electromagnetic field frequency of 1 kHz, electrochemical scale removal device voltage of 24 V, current of 10 A, and water flow rate of 0.6 m/s, the transformation of calcite to aragonite in CaCO₃ scale samples occurred, with a 76.6% increase in aragonite content. Moreover, the conductivity decreased by 11.6%, hardness decreased by 42.0%, COD decreased by 59.7%, turbidity decreased by 48.1%, and chloride and iron ion concentrations decreased by 36.6% and 63.1%, respectively. The scale inhibition efficiency reached 53.8%, surpassing the effects of electromagnetic and electrochemical actions individually. These findings demonstrate that the combined action of electromagnetic and electrochemical fields can effectively enhance scale inhibition, scale removal, corrosion inhibition, and disinfection and algae removal effects. Full article

This paper outlines the numerical modeling procedure aimed at defining the guidelines for the development of a continuous microwave-assisted pilot plant for shelled almond disinfestation, as an alternative to the use of chemicals. To this end, a 3D Multiphysics numerical tool involving both electromagnetic and thermal models was developed to predict the temperature and electric field profiles inside the microwave treatment chamber. Three different microwave sources arrangements were simulated and the accuracy of the model was verified under different residence times of almonds in the treatment chamber using the developed prototype. The modeling results demonstrated that the arrangement having five microwave sources, each delivering a maximum power of 1.5 kW and frequency of 2.45 GHz, ensures good heating uniformity. The obtained results proved that the model enables the accurate prediction of the temperature trend (root-mean-square error/RMSE = 0.82). A strong linear regression was detected for the standard deviation between the simulated and experimental data (linear regression, R² = 0.91). The very low COV value for the experimental temperature data demonstrated the heating uniformity as the treatment time changed. The developed model and the simulation strategy used may provide useful design guidance for microwave-assisted continuous plants for disinfestation, with a significant impact on the almond industry. Full article

With the system interconnection and intelligence of application scenario equipment, the electromagnetic environment of chips is becoming more and more complex. Problems such as communication interruption and data loss caused by electromagnetic interference often occur. The electromagnetic reliability of chips has become an important index to measure their availability. In order to effectively detect the electromagnetic reliability of industrial chips applied to specific scenarios, it is necessary to measure and analyze the electromagnetic characteristics of the application scenarios, as the boundary conditions of the electromagnetic protection simulation analysis and design of the chip, and to develop Electromagnetic Compatibility (EMC) test items, test limits and test methods suitable for carrying out tests and monitoring on chips. The paper presents an acquisition system, which can complete the collection of transient electromagnetic interference, steady electromagnetic field, temperature, humidity and near-field data. The transient interference measurement frequency range is 300 kHz–500 MHz, with a rising edge of 1.5 ns; the steady-state electromagnetic field measurement frequency ranges from 100 Hz to 3 GHz. By collecting the electromagnetic environmental characteristics of chips and analyzing situations in which chips are prone to interference, protective measures can be implemented. Full article

Radio-frequency identification technology finds extensive use in various industrial applications, including those involving metallic surfaces. The integration of radio-frequency identification systems with metal surfaces, such as those found in the automotive sector, presents distinct challenges that can notably affect system efficacy due to metal’s tendency to reflect electromagnetic waves, thus degrading the functionality of conventional radio-frequency identification tags. This highlights the importance of conducting research into academic publications and patents to grasp the current advancements and challenges in this field, aiming to improve the applications of radio-frequency identification tags technology on metal. Consequently, this research undertakes a concise review of both the literature and patents exploring radio-frequency identification technology’s use for on-metal tags, utilizing resources like Google Scholar and Google Patents. The research categorized crucial aspects such as tag flexibility, operating frequency, and geographic origins of the research. Findings highlight China’s prominent role in contributing to metal-focused radio-frequency identification tag research, with a considerable volume of articles and patents. In particular, flexible tags and the Ultra-High Frequency range are dominant in both scholarly and patent documents, reflecting their significance in radio-frequency identification technology applications. The research underscores a vibrant area of development within radio-frequency identification technology, with continued innovation driven by specific industrial needs. Despite the noted advances, the presence of a significant percentage of no longer valid patents suggests substantial opportunities for further research and innovation in radio-frequency identification technology for on-metal applications, especially considering the demand for flexible tags and for solutions in systems that offer specialized characteristics or are tailored for specific uses. Full article

Anthropogenic radiofrequency electromagnetic radiation (RF-EMR) from wireless technologies has increased dramatically. The boar semen used for artificial insemination is essential in sustaining the pig industry, and additionally it is also exposed to the effects of the RF-EMR of wireless technologies. Furthermore, there are no data on the effects of RF-EMR on semen quality, and this is the first analysis of sperm’s morphometric parameters for assessing the effect of RF-EMR on the spermatozoa subpopulations of boars. This study investigated the effect of RF-EMR on in vitro exposed breeding boar semen spermatozoa motility and the proportions of spermatozoa subpopulations according to their morphometric head and tail parameters. The semen samples of 12 boars were divided into control and experimental groups. The samples in the experimental group were exposed in a gigahertz transverse electromagnetic chamber at a frequency of 2500 MHz (the frequency band used in 5G technology) and an electric field strength of 10 Vm⁻¹ for two hours. After exposure, the spermatozoa motility was evaluated for both groups. A morphometric analysis of the semen smears was performed using SFORM software (Version 1.0; VAMS, Zagreb, Croatia). The progressive spermatozoa motility was significantly reduced in the experimental group (74.7% vs. 85.7%). PC analysis and cluster analysis revealed two spermatozoa subpopulations: S1, spermatozoa with a more regular head shape and a smaller midpiece outline, and S2, spermatozoa with a more elongated head shape and a larger midpiece outline. The experimental semen samples had a greater proportion of the S1 spermatozoa subpopulation (68.2% vs. 64.4%). The effect of RF-EMR at 2500 MHz on the in vitro exposed boar semen resulted in decreased progressive spermatozoa motility and a lower proportion of the spermatozoa subpopulation with a higher fertilizing potential. Full article