Search Results (4,765)

The electromagnetic density of states (EM-DOS) plays a crucial role in understanding light–matter interactions, especially at metal–dielectric interfaces. This study explores the impact of interface geometry, material properties, and nanostructures on EM-DOS, with a focus on surface plasmon polaritons (SPPs) and evanescent waves. Using a combination of analytical and numerical methods, the behavior of EM-DOS is analyzed as a function of distance from metal–dielectric interfaces, showing exponential decay with penetration depth. The influence of different metals, including copper, gold, and silver, on EM-DOS is examined. Additionally, the effects of dielectric materials, such as Ti${\mathrm{O}}_2$, PMMA, and ${\mathrm{Al}}_2$${\mathrm{O}}_3$, on the enhancement of electromagnetic field confinement are discussed. The study also investigates the effect of nanostructures, like nanohole and nanopillar arrays, on EM-DOS by calculating effective permittivity and analyzing the interaction of quantum emitters with these structures. Results show that nanopillar arrays enhance EM-DOS more effectively than nanohole arrays, especially in the visible spectrum. The findings provide insights into optimizing plasmonic devices for applications in sensing, quantum technologies, and energy conversion. Full article

Exposure of individuals to electromagnetic fields in a wide area of daily life necessitated making spaces-structures healthier against electromagnetic fields. In this study, waste copper slag and carbon fibers were added to the cement mortar in different proportions with substitutes and additives. Physical, mechanical, electromagnetic shielding and microstructure studies were carried out on the produced composite mortars at different ages. It was determined that the mechanical strengths of composite mortars were superior to those of reference mortar samples. It was observed that electromagnetic shielding effectiveness was more positive with copper slag and especially carbon fiber additions. The highest electromagnetic shielding values were obtained in mortars containing 50% copper slag and 0.5% carbon fiber. Additionally, it was determined that copper slag, stored as an environmental waste, could be suitable for use in cementitious mortar systems. These composites offer promise for sustainable building designs in terms of both environmental performance and structural material stability. Full article

Accurate and real-time monitoring of low-frequency electromagnetic field (EMF) is essential in power and industrial environments, yet most conventional approaches still suffer from limited spatial coverage, manual operation, and insufficient digitization. To address these challenges, this paper proposes an intelligent EMF monitoring system that integrates six-axis magnetic field sensing, temperature compensation, vector synthesis, Sub-1 GHz wireless communication, and real-time data visualization. The system supports simultaneous measurement of both AC and DC magnetic fields across the 30 Hz–100 kHz range, with specific optimization for power-frequency conditions (50/60 Hz). Designed with modular integration and low power consumption, it is suitable for portable deployment in field scenarios. Comprehensive laboratory and substation tests demonstrate high accuracy, with maximum measurement errors of 1.17% under zero-field and 1.42% under applied-field conditions—well below the ±5% tolerance defined by international standards. Wireless performance tests further confirm stable long-distance communication, achieving ranges of up to 5 km without significant transmission errors, while overall system measurement error reached as low as 0.015%. These results verify the system’s robustness, fidelity, and compliance with international safety standards. Overall, the proposed platform provides a practical and scalable solution for intelligent EMF monitoring, offering strong potential for deployment in industrial environments and infrastructure-critical applications. Full article

Wireless pipeline robots often suffer from localization drift and position loss due to electromagnetic attenuation and shielding in complex pipeline configurations, which hinders accurate pipeline reconstruction. This paper proposes a trajectory reconstruction method based on Geometric Constraint–Long Short-Term Memory (GC-LSTM). First, a motor control system based on Field-Oriented Control (FOC) was developed for the proposed pipeline robot; second, trajectory errors are mitigated by exploiting pipeline geometric characteristics; third, a Long Short-Term Memory (LSTM) network is used to predict and compensate the robot’s velocity when odometer slip occurs; finally, multi-sensor fusion is employed to obtain the reconstructed trajectory. In straight-pipe tests, the GC-LSTM method reduced the maximum deviation and mean absolute deviation by 69.79% and 72.53%, respectively, compared with the Back Propagation (BP) method, resulting in a maximum deviation of 0.0933 m and a mean absolute deviation of 0.0351 m. In bend-pipe tests, GC-LSTM reduced the maximum deviation and the mean absolute deviation by 60.48% and 69.91%, respectively, compared with BP, yielding a maximum deviation of 0.2519 m and a mean absolute deviation of 0.0850 m. The proposed method significantly improves localization accuracy for wireless pipeline robots and enables more precise reconstruction of pipeline environments, providing a practical reference for accurate localization in pipeline inspection applications. Full article

Understanding flow dynamics in open-channel node systems is crucial for designing effective hydraulic engineering solutions and minimizing energy losses. This study investigates how junction geometry—specifically the lateral inflow angle (α = 45° and 60°) and the longitudinal bed slope (I = 0.0011 to 0.0051)—influences the water velocity distribution and hydraulic losses in a rigid-bed Y-shaped open-channel junction. Experiments were performed in a 0.3 m wide and 0.5 m deep rectangular flume, with controlled inflow conditions simulating steady-state discharge scenarios. Flow velocity measurements were obtained using a PEMS 30 electromagnetic velocity probe, which is capable of recording three-dimensional velocity components at a high spatial resolution, and electromagnetic flow meters for discharge control. The results show that a lateral inflow angle of 45° induces stronger flow disturbances and higher local loss coefficients, especially under steeper slope conditions. In contrast, an angle of 60° generates more symmetric velocity fields and reduces energy dissipation at the junction. These findings align with the existing literature and highlight the significance of junction design in hydraulic structures, particularly under high-flow conditions. The experimental data may be used for calibrating one-dimensional hydrodynamic models and optimizing the hydraulic performance of engineered channel outlets, such as those found in hydropower discharge systems or irrigation networks. Full article

Magnetocardiography (MCG) offers a noninvasive method for early screening and precise localization of cardiovascular diseases by measuring picotesla-level weak magnetic fields induced by cardiac electrical activity. However, in unshielded magnetic environments, geomagnetic disturbances, power-frequency electromagnetic interference, and physiological/motion artifacts can significantly overwhelm effective magnetocardiographic components. To address this challenge, this paper systematically constructs an integrated denoising framework, termed “AOA-VMD-WT”. In this approach, the Arithmetic Optimization Algorithm (AOA) adaptively optimizes the key parameters (decomposition level K and penalty factor α) of Variational Mode Decomposition (VMD). The decomposed components are then regularized based on their modal center frequencies: components with frequencies ≥50 Hz are directly suppressed; those with frequencies <50 Hz undergo wavelet threshold (WT) denoising; and those with frequencies <0.5 Hz undergo baseline correction. The purified signal is subsequently reconstructed. For quantitative evaluation, we designed performance indicators including QRS amplitude retention rate, high/low frequency suppression amount, and spectral entropy. Further comparisons are made with baseline methods such as FIR and wavelet soft/hard thresholds. Experimental results on multiple sets of measured MCG data demonstrate that the proposed method achieves an average improvement of approximately 8–15 dB in high-frequency suppression, 2–8 dB in low-frequency suppression, and a decrease in spectral entropy ranging from 0.1 to 0.6 without compromising QRS amplitude. Additionally, the parameter optimization exhibits high stability. These findings suggest that the proposed framework provides engineerable algorithmic support for stable MCG measurement in ordinary clinic scenarios. Full article

The appearance of a negative mass term in the classical, non-relativistic Klein–Gordon equation deduced from mechanical interactions describes a repulsive interaction. In the case of a traveling wave, this results in an increase in amplitude and a decrease in the wave propagation velocity. Since this leads to dissipation, it is a symmetry-breaking phenomenon. After the repulsive interaction is eliminated, the system evolves towards the original state. Given that the interactions within the system are conservative, it would be assumed that even the original state is restored. The analysis to be presented shows that a wave with a lower angular frequency than the original one is transformed back to a slightly larger amplitude. This description is a suitable model of the axion effect, during which an electromagnetic wave interacts with a repulsive field and becomes of a continuously lower frequency. Full article

This research paper presents the results of an analysis conducted on a microstrip patch antenna designed to operate within the 1.559–1.591 GHz frequency band, which encompasses three major satellite constellations: GPS, Galileo and BeiDou. The objective of this study is to perform a comparative evaluation of the materials used in the antenna design, assess the geometric configuration and analyze the key performance parameters of the proposed microstrip patch antenna. Prior to the numerical modeling and simulation process, a preliminary assessment was conducted to evaluate how different substrate materials influence antenna efficiency. For instance, a comparison between FR-4 and RT Duroid 5880 dielectric substrates revealed signal attenuation differences of approximately −1 dB at the target frequency. The numerical simulations were carried out using Ansys HFSS design. The antenna was mounted on a dielectric substrate, which was also mounted on a ground plane. The microstrip antenna was fed using a coaxial cable at a single point, strategically positioned to achieve circular polarization within the operating frequency band. The aim of this study is to design and analyze a microstrip antenna that operates within the previously specified frequency range, ensuring optimal impedance matching of 50 Ω with a return loss of S₁₁ < −10 dB at the operating frequency (with these parameters also contributing to the definition of the antenna’s operational bandwidth). Furthermore, the antenna is required to provide a gain greater than 3 dB for integration into GNSS’ receivers and to achieve an Axial Ratio value below 3 dB in order to ensure circular polarization, thereby facilitating the antenna’s integration into GNSSs. Full article

Advanced energy storage solutions are required to mitigate grid destabilization caused by high-penetration renewable energy integration. Superconducting Magnetic Energy Storage (SMES) offers ultrafast response (<1 ms), high efficiency (>95%), and almost unlimited cycling life. However, its commercialization is hindered by the complex modeling of critical current with anisotropic behaviors and the computational inefficiency of high-dimensional optimization for megajoule (MJ)-class magnets. This paper proposes an integrated design framework synergizing a two-dimensional axisymmetric magnetic field model based on Conway’s current-sheet theory, a critical current anisotropy characterization model, and an adaptive genetic algorithm (AGA). A superconducting magnet optimization model incorporating co-calculation of electromagnetic parameters is established. A dual-module chromosome encoding strategy (discrete gap index + nonlinear increment) and parallel acceleration techniques were developed. This approach achieved efficient optimization of MJ-class magnets. For a single solenoid, the critical current increased by 22.6% (915 A) and energy storage capacity grew by 41.8% (1.12 MJ). A 20-unit array optimized by coordinated gap adjustment achieved a matched inductance/current of 0.15 H/827 A (20 MJ), which can enhance transient stability control capability in smart grids. The proposed method provides a computationally efficient design paradigm and user-friendly teaching software tool for high-current SMES magnets, supporting the development of large-scale High-Temperature Superconducting (HTS) magnets, promoting the deployment of large-scale HTS magnets in smart grids and high-field applications. Full article

Approaches to magnetotelluric monitoring of variations in apparent resistivity and electromagnetic emission that may serve as earthquake precursors are considered. Monitoring of apparent resistivity is advised in the range 7–300 Hz, where natural electromagnetic fields exhibit stable behavior, while at lower frequencies the behavior of the electrotelluric and magnetic fields should be analyzed. We present results of studies aimed at identifying active faults and searching for stress–strain sensitive zones for installing measurement equipment based on the registration of tidal variations in apparent resistivity. The features of apparent resistivity anomalies preceding earthquakes in China based on direct current measurements are discussed. Based on the analysis of natural electromagnetic field monitoring in the ULF and ELF ranges in China, the anomalies recorded prior to several recent earthquakes are considered. Before the Yangbi earthquake (2017) and the series of Yangbi (2021) and Ninglang (2022) earthquakes, variations in apparent resistivity were observed that have a pulsed behavior and probably are manifestations of electromagnetic emission. Possible sources of these anomalies are active faults located near the monitoring stations. Full article

We present three dimensional particle-in-cell simulations of current-voltage characteristics of the hemispherical Langmuir probe (LAP), onboard the China Seismo-Electromagnetic Satellite (CSES). Using realistic plasma parameters and background magnetic fields obtained from the International Reference Ionosphere (IRI) and International Geomagnetic Reference Field (IGRF) models, we simulate probe–plasma interactions at three locations: the equatorial region and two magnetically conjugate mid-latitude sites: Millstone Hill (Northern Hemisphere) and Rothera (Southern Hemisphere). The simulations, performed using the PTetra PIC code, incorporate realistic LAP geometry and spacecraft motion in the ionospheric plasma. Simulated current voltage characteristics or I–V curves are compared against in-situ LAP measurements from CSES Orbit-026610, with Pearson’s correlation coefficients used to assess agreement. Our findings indicate how plasma temperature, density, and magnetization affect sheath structure and probe floating potential. The study highlights the significance of kinetic modeling in enhancing diagnostic accuracy, particularly in variable sheath regimes where classic analytical models such as the Orbital-Motion-Limited (OML) theory may be inadequate. Full article

Background: Diabetes mellitus is a heterogeneous chronic disease with an increasing global prevalence. In Romania, 11.6% of the population is affected, yet only 6.46% receive treatment. Among diabetic patients, 15–25% develop skin lesions that may progress to ulceration and necrosis, significantly impairing quality of life and increasing the risk of complications. Methods: We conducted a prospective study including 28 patients (14 in the control group and 14 in the intervention group) with type I or II diabetes and chronic ulcers of the calf or foot (>4 cm²). The control group received standard therapy with debridement, dressings, antibiotics when indicated, and local and systemic ozone therapy. The intervention group was treated with an Integrative Therapeutic Protocol combining ozone therapy, pulsed electromagnetic field therapy (PEMF), colon hydrotherapy with probiotic supplementation, and an anti-inflammatory alkaline diet. Wound healing (reduction in ulcer surface area) was the primary endpoint; secondary endpoints included changes in glycemia and inflammatory biomarkers. Results: After 8 weeks, the intervention group achieved 86.2% re-epithelialization versus 58.2% in controls (p < 0.01). Significant improvements were also observed in blood glucose level (−38%), HbA1c (−25%), CRP (−26%), and fibrinogen (−28%) relative to baseline, with differences versus controls reaching statistical significance. Conclusions: The Integrative Therapeutic Protocol accelerated wound healing and improved glycemic and inflammatory profiles compared with ozone therapy alone. Although an alkaline diet was recommended, adherence and its specific contribution were not objectively monitored; therefore, this component should be interpreted with caution. Full article

In complex electromagnetic environments, traditional static absorbers struggle to meet dynamic control requirements. Tunable absorbers based on metasurfaces have emerged as a research hotspot due to their ability to flexibly control electromagnetic wave properties. This paper provides a systematic review of research progress in tunable absorbers across the microwave, terahertz, and infrared bands, with a focus on analyzing the physical mechanisms, material systems, and performance characteristics of five dynamic control methods: electrical control, magnetic control, optical control, temperature control, and mechanical control. Electrical control achieves rapid response through materials such as graphene and varactor diodes; magnetic control utilizes ferrites and other materials for stable tuning; optical control relies on photosensitive materials for ultrafast switching; temperature control employs phase-change materials for large-range reversible regulation; and mechanical control expands tuning freedom through structural deformation. Research indicates that multi-band compatibility faces challenges due to differences in structural scale and physical mechanisms, necessitating the integration of emerging materials and synergistic control strategies. This paper summarizes the core performance metrics and typical applications of absorbers across various bands and outlines future development directions such as multi-field synergistic control and low-power design, providing theoretical references and technical pathways for the development of intelligent tunable absorber devices. Full article

To explore the influence of double-electrode regulation technology on the solidification microstructure and properties of GCr15 bearing steel, the double-electrode insertion process was employed in this study, combined with metallographic analysis, mechanical property testing, and electron probe composition characterization. We analyzed the mechanisms of solidification microstructure evolution and mechanical property improvement, as well as the composition segregation control effect, of GCr15 steel under double-electrode regulation. The results show that the double-electrode technology significantly refines the microstructure and improves the internal quality of the ingot by optimizing the temperature field and electromagnetic field distribution in the molten pool and enhancing the internal flow of the melt. The tensile strengths in the upper and middle parts were increased by 84.6% and 29.6%, respectively, which can be attributed to the uniform distribution of carbides at the grain boundaries and the reduction of segregation. Composition analysis indicates that the macroscopic segregation index of C element was decreased under the dual-electrode process. This research provides a theoretical basis and process optimization direction for the high-quality preparation of high-carbon chromium bearing steel. Full article

The reliability of the generator circuit breaker (GCB) switching coil affects the safe and stable operation of the power system, in which the faults of abnormal voltage, poor contact, and mechanical jamming of the switching coil can easily lead to the refusal of the circuit breaker, which threatens the safety of the power grid. In order to study the fault characteristics of the GCB switching coil, this paper combines multi-physical field simulation and experimental testing, establishes the electromagnetic field simulation model of the switching coil, and analyzes the characteristics of current waveforms under typical faults such as voltage abnormality, poor contact, and core jamming. Through simulation and testing to verify the mechanism of current waveform distortion under different fault states, demonstrated the change rule of characteristic parameters when the fault occurs, and provided a basis for the diagnosis of the operation status of the switching coil based on current waveform. Full article