Search Results (2,898)

This study sought to evaluate the inhibitory effect of pulsed electromagnetic field (PEMF) therapy on bone resorption in a mouse model of lipopolysaccharide (LPS)-induced osteoporosis. A total of 40 mice were divided into four groups: control, LPS, LPS + alendronate, and LPS + PEMF. Blood and spleen samples were analyzed using RT-PCR and ELISA, while calvaria and femurs were assessed by micro-computed tomography (CT) and histological analysis. Serum analysis revealed that, compared with the control group, calcium levels in the PEMF group showed no significant difference, but alkaline phosphatase (ALP) levels were significantly increased, whereas tartrate-resistant acid phosphatase (TRAP) levels were significantly decreased. Moreover, blood cytokine analysis showed reduced expression of TNF-α and IL-1β and increased expression of BMP-2 in the PEMF group. Spleen tissue analysis further demonstrated significant upregulation of IFN-γ and IL-10 expression in the PEMF group. Micro-CT confirmed that PEMF inhibited femoral bone loss and promoted bone regeneration in calvarial defects. Histological evaluation with hematoxylin and eosin and Masson–Goldner trichrome staining confirmed enhanced bone formation in both the femur and calvaria. In conclusion, PEMF effectively alleviates bone loss and promotes bone regeneration in LPS-induced osteoporosis. Furthermore, PEMF exhibits anti-osteoclastogenic activity by reducing inflammatory cytokines and enhancing IFN-γ and IL-10 expression in the spleen. Full article

The ground small-loop transient electromagnetism (TEM) provides a basis for detecting shallow underground space. However, the strong primary field interference from the transmitting coil to the receiving coil, along with the transition process of the receiving coil, can cause serious distortion of the early secondary field signals. This leads to the loss of effective shallow underground information. In this paper, we utilize the eccentric self-compensating structure to weaken the primary field interference. Aiming at the current position sensitivity of the eccentric structure, we propose a statistical method to realize the robustness analysis of the eccentric structure and find the optimal eccentric position where the primary field coupling between the transmitting and receiving coil is approximated to be zero. To address the impact of the coil transition process, a double receiving coils structure is proposed. This ensures that the number of turns, the secondary field flux and the secondary field response strength in the single receiving coil structure remain unchanged. Compared with the conventional eccentric structure of a single receiving coil, the bandwidth of the receiving coil sensor was increased from 103.5 kHz to 218.3 kHz, and the Signal-to-Noise Ratio (SNR) of the measured early secondary field signals improved from 18.5 to 27.9, representing a 50.81% increase in SNR. This study not only reduces primary field interference but also reduces the impact of the coil transition process, thereby capturing more early secondary field signals and enhancing the shallow detection resolution of the ground TEM. Full article

In this paper, a method for determining the optimal stator-rotor combinations of conventional flux-switching permanent magnet (FSPM) machines with composite phase numbers covering symmetrical and asymmetrical topologies is proposed by changing the equivalent number of coils per pole per phase (ENCPP) or the number of coil-pairs having complementarity (K) of the optimal stator-rotor combinations of the corresponding machines with prime phases. Taking composite phase machines such as four-phase, six-phase, nine-phase, and twelve-phase machines as examples, a detailed analysis is conducted on how the optimal stator-rotor combinations of four-phase machines are derived from the optimal stator-rotor combinations of the corresponding prime phase machines (i.e., two-phase machines) and how the optimal stator-rotor combinations of six-phase, nine-phase, and twelve-phase machines are derived from the optimal stator-rotor combinations of the corresponding prime phase machines (i.e., three-phase machines). Then, the winding factor of the conventional FSPM machines with composite phase numbers is calculated. Finally, taking a 24-slot/22-tooth (24/22) conventional FSPM topology as an example, the topology is connected into a standard six-phase machine (symmetrical topology) and a dual three-phase machine (asymmetrical topology), and a comparative study between them is conducted in terms of the phase back electromotive force (EMF) waveform, electromagnetic torque, torque ripple, and inductances. The results indicate that both machines have sufficiently large and symmetrical back-EMFs, as well as sufficiently large electromagnetic torque, which validates the correctness of the proposed method for determining the optimal stator-rotor combinations. Full article

To model the response of neural networks to electromagnetic radiation in real-world environments, this study proposes a memristive dual-wing fractional-order Hopfield neural network (MDW-FOMHNN) model, utilizing a fractional-order memristor to simulate neuronal responses to electromagnetic radiation, thereby achieving complex chaotic dynamics. Analysis reveals that within specific ranges of the coupling strength, the MDW-FOMHNN lacks equilibrium points and exhibits hidden chaotic attractors. Numerical solutions are obtained using the Adomian Decomposition Method (ADM), and the system’s chaotic behavior is confirmed through Lyapunov exponent spectra, bifurcation diagrams, phase portraits, and time series. The study further demonstrates that the coupling strength and fractional order significantly modulate attractor morphologies, revealing diverse attractor structures and their coexistence. The complexity of the MDW-FOMHNN output sequence is quantified using spectral entropy, highlighting the system’s potential for applications in cryptography and related fields. Based on the polynomial form derived from ADM, a field programmable gate array (FPGA) implementation scheme is developed, and the expected chaotic attractors are successfully generated on an oscilloscope, thereby validating the consistency between theoretical analysis and numerical simulations. Finally, to link theory with practice, a simple and efficient MDW-FOMHNN-based encryption/decryption scheme is presented. Full article

The reliability of power supply systems is of utmost importance for telecommunications. In our daily lives, we are used to having constant access to the power grid with negligible risks. Standards and practices established over the years guarantee minimal problems for the household consumer and accidents in their electrical appliances. Often, the biggest inconvenience of a power failure for the average person is having to set the clock on the stove or use the flashlight on their phone. However, we rarely realize how fragile the balance on which all this is based is, but telecom companies are fully aware of this fact. Regardless of whether the problem comes from natural phenomena, accidental or intentional damage, or defects in the equipment, the equipment used in telecommunications technologies is extremely sensitive, and it is necessary to take protective measures. Full article

Aiming at the problem of a lack of positioning satellites and no available beacons in underground space, an injected ground electrode current field signal localization method is proposed. An extremely low-frequency current field signal is applied to two pairs of electrodes inserted into the earth to form a ground current field underground, and the ground electrode current field signal detected at the detection end is used for localization, which can effectively provide reference localization for the underground space when the satellite positioning fails. On this basis, considering that the ground electrode current field signal is susceptible to the influence of the geological structure, electromagnetic interference, and the complexity of the propagation path during underground transmission, which results in the signal showing strong non-stationary characteristics, it is difficult for the traditional time–frequency analysis method to accurately extract stable and reliable positioning characteristics. In order to improve the signal-processing accuracy and robustness, this paper introduces fractional Fourier transform (FRFT) to process the detected signals, and focuses the signal energy more effectively under the optimal order. In order to verify the effectiveness of the localization method, several experiments on the localization of ground electrode current field signals are carried out in the underground space. The experimental results show that, in the positioning environment of more than 10,000 square meters, the average positioning error is 6.896 m. The application of this method will provide a solid technical support for life rescue in underground space, provide the ‘last protection’ for rescue, and complete the life chain of emergency first aid, which has an important application prospect and practical value. Full article

This study focuses on a comprehensive analysis of the common methods for road infrastructure monitoring, as well as the perspective of various fiber-optic sensor (FOS) realization solutions in road monitoring applications. Fiber-optic sensors are a topical technology that ensures multiple advantages such as passive nature, immunity to electromagnetic interference, multiplexing capabilities, high sensitivity, and spatial resolution, as well as remote operation and multiple physical parameter monitoring, hence offering embedment potential within the road pavement structure for needed smart road solutions. The main key factors that affect FOS-based road monitoring scenarios and configurations are analyzed within this review. One such factor is technology used for optical sensing—fiber Bragg grating (FBG), Brillouin, Rayleigh, or Raman-based sensing. A descriptive comparison is made comparing typical sensitivity, spatial resolution, measurement distance, and applications. Technological approaches for monitoring physical parameters, such as strain, temperature, vibration, humidity, and pressure, as a means of assessing road infrastructure integrity and smart application integration, are also evaluated. Another critical aspect concerns spatial positioning, focusing on the point, quasi-distributed, and distributed methodologies. Lastly, the main topical FOS-based application areas are discussed, analyzed, and evaluated. Full article

This study employs molecular orbital (MO) analysis, density of states (DOS) analysis, and advanced techniques such as charge density difference (CDD), transition density matrix (TDM), transition electric dipole moment density (TEDM), and transition magnetic dipole moment density (TMDM) to systematically investigate the electronic structure characteristics of Fc-[8]CPP and Fc-[11]CPP. Using density functional theory (DFT) and time-dependent DFT (TD-DFT), the π-electron delocalization properties and optical behaviors of these molecules were analyzed. Furthermore, their responses to external electromagnetic fields were explored through electronic circular dichroism (ECD) and Raman spectroscopy, comparing chiral optical responses and electron–vibration coupling effects to elucidate their photophysical properties. The results reveal that the HOMO-LUMO energy gaps of Fc-[8]CPP and Fc-[11]CPP are 5.81 eV and 5.95 eV, respectively, with a slight increase as ring size grows; Fc-[8]CPP exhibits a stronger chiral response, while Fc-[11]CPP shows reduced chirality due to enhanced symmetry. Finally, TD-DFT calculations demonstrate that their optical absorption is dominated by localized excitations with partial charge transfer contributions. These findings provide a theoretical foundation for designing conjugated macrocyclic materials with superior optoelectronic performance. Full article

In this study, we investigate the dominant electromagnetic wave absorption mechanism–ferromagnetic resonance (FMR) loss versus quarter-wave cancellation in a novel PVDF-based polymer composite embedded with carbonaceous nanostructures incorporating FeCoCr ternary alloy. The majority of the nanoparticles are embedded at the terminal ends of the carbon nanotubes, while a small fraction exists as isolated core–shell, carbon-coated spherical particles. Overall, the synthesized material predominantly exhibits a nanotubular carbon morphology. High-resolution transmission electron microscopy (HRTEM) confirms that the encapsulated nanoparticles are quasi-spherical in shape, with an average size ranging from approximately 25 to 40 nm. The polymeric composite was synthesized via solution casting, ensuring homogenous dispersion of filler constituent. Electromagnetic interference (EMI) shielding performance and reflection loss characteristics were evaluated in the X-band frequency range. Experimental results reveal a significant reflection loss exceeding −20 dB at a matching thickness of 2.5 mm, with peak absorption shifting across frequencies with thickness variation. The comparative analysis, supported by quarter-wave theory and FMR resonance conditions, indicates that the absorption mechanism transitions between magnetic resonance and interference-based cancellation depending on the material configuration and thickness. This work provides experimental validation of loss mechanism dominance in magnetic alloy/polymer composites and proposes design principles for tailoring broadband microwave absorbers. Full article

Aiming at the drawback of unstable torque output caused by heat generation due to slip in magnetorheological fluid transmission devices, this paper proposes a new type of non-coaxial conical disk magnetorheological fluid transmission structure and deduces its mathematical model of output torque. The magnetic circuit design was carried out based on the conical disk configuration. The electromagnetic field analysis of the transmission device was conducted by the finite element method, and the influence laws of parameters such as the coil current, magnetic conductive material, the conical angle of the disk, and the working gap on the distribution of the magnetic induction intensity in the working area were obtained. The test system for the non-coaxial conical disk type magnetorheological fluid transmission device was established, and experiments on electromagnetic fields, transmission performance, torque response, etc., were carried out. Research results show that the magnetic induction intensity in the working area increases with the increase of the current in the excitation coil, decreases with the increase of the working gap between the two conical disks, and is positively correlated with the magnetic permeability of the conical disk and the magnetic conducting ring materials. The effective working area range and magnetic induction intensity of the governor both decrease as the conical angle of the disk increases. The magnitude of the magnetic induction intensity on the center line is basically the same, but the effective working area range corresponding to different angles shows significant differences. Full article

This work presents an end-to-end encryption–decryption framework for securing electromagnetic signals processed through a nanoantenna. The system integrates amplitude normalization, uniform quantization, and Reed–Solomon forward error correction with key establishment via ECDH and bitwise XOR encryption. Two signal types were evaluated: a synthetic Gaussian pulse and a synthetic voice waveform, representing low- and high-entropy data, respectively. For the Gaussian signal, reconstruction achieved an RMSE = 11.42, MAE = 0.86, PSNR = 26.97 dB, and Pearson’s correlation coefficient = 0.8887. The voice signal exhibited elevated error metrics, with an RMSE = 15.13, MAE = 2.52, PSNR = 24.54 dB, and Pearson correlation = 0.8062, yet maintained adequate fidelity. Entropy analysis indicated minimal changes between the original signal and the reconstructed signal. Furthermore, avalanche testing confirmed strong key sensitivity, with single-bit changes in the key altering approximately 50% of the ciphertext bits. The findings indicate that the proposed pipeline ensures high reconstruction quality with lightweight encryption, rendering it suitable for environments with limited computational resources. Full article

Optical fiber-based biosensors have proven to be a powerful platform for chemical and biological analysis due to their compact size, fast response, high sensitivity, and immunity to electromagnetic interference. Among the various fiber designs, tapered optical fibers have gained prominence due to the increased evanescent fields that significantly improve light–analyte interactions, making them well-suited for advanced sensing applications. At the same time, advances in microfluidics have allowed for the precise control of small-volume fluids, supporting integration with optical fiber sensors to create compact and multifunctional optofluidic systems. This review explores recent developments in optical fiber optofluidic sensing, with a focus on two primary architectures: in-fiber and outside-fiber platforms. The advantages, limitations, and fabrication strategies for each are discussed, along with their compatibility with various sensing mechanisms. Special emphasis is placed on tapered optical fibers, focusing on design strategies, fabrication, and integration with microfluidics. While in-fiber systems offer compactness and extended interaction lengths, outside-fiber platforms offer greater mechanical stability, modularity, and ease of functionalization. The review highlights the growing interest in tapered fiber-based optofluidic biosensors and their potential to serve as the foundation for autonomous lab-on-a-fiber technologies. Future pathways for achieving self-contained, multiplexed, and reconfigurable sensing platforms are also discussed. Full article

Concrete sleepers are essential components of railroad infrastructure, yet their service life has been reduced by one-third due to deterioration caused by internal swelling reactions (ISR), leading a major Brazilian railroad to replace millions of sleepers within a decade. This study investigates the reliability of various non-destructive testing (NDT) techniques to estimate damage levels in concrete sleepers. The methods evaluated include surface hardness testing, stress wave propagation, electromagnetic wave propagation using ground-penetrating radar (GPR), electrical resistivity, and resonant frequency. These techniques were applied to assess sleepers diagnosed as affected by alkali-silica reaction (ASR) and delayed ettringite formation (DEF) at different deterioration degrees. Although findings indicate that most NDT methods are limited and unreliable for quantifying ISR-induced damage, resonant frequency testing combined with energy dissipation analysis provided the highest accuracy across all damage stages and was able to capture microstructural changes before significant expansion occurred. These results support the use of vibration-based screening tools to enhance early detection and guide condition assessment of railroad infrastructure, helping to reduce the premature replacement of ISR-affected concrete sleepers. Full article

Litz wires are extensively employed in contemporary high-frequency switching power electronics to mitigate conductor losses. Minimizing additional winding losses caused by high-frequency phenomena, such as skin and proximity effects, is a critical design consideration for achieving high power density in modern power electronics. However, accurately predicting losses in structures composed of numerous twisted and insulated strands remains a challenge. With the increasing accessibility of commercial numerical tools, such as finite element method (FEM) solvers, simulation-based approaches have become indispensable tools for analyzing electromagnetic phenomena in complex magnetic device structures under high-frequency conditions. In parallel, data-driven modeling has emerged as a powerful method, enabling pattern identification based on datasets; however, such approaches rely on the availability of large amounts of reliable high-quality data. Generating such large-scale FEM datasets, however, is often constrained by long computation times and high memory consumption. Despite the remarkable advancements in computing power, full three-dimensional (3D) FEM analysis at the strand level for Litz wire windings often remains infeasible within personal computing environments. To address these challenges, this study presents a computationally efficient two-dimensional FEM-based framework that integrates a data-driven fitting model with optimized geometric discretization and meshing strategies, enabling accurate analysis with reduced computational load. The proposed approach, which incorporates optimal meshing conditions into commercially available 2D FEM tools and a simple data-driven fitting model, enables accurate prediction of the frequency-dependent AC resistance of multi-turn Litz windings using a typical personal computer. Its feasibility is further demonstrated through experimental frequency response measurements on both 12-turn and 21-turn windings fabricated with 150-strand Litz wire, which show strong agreement with the corrected simulation results, confirming the model’s accuracy and practical applicability. Full article

Smart monitoring of local electricity systems (LESs) with sources based on renewable energy resources (RESs) from the point of view of the requirements of the functions of an intelligent system are hardware and software systems that can solve the tasks of both analysis (optimization) and synthesis (design, planning, control). The article considers the following: a functional scheme of smart monitoring of LESs, describing its main components and scope of application; an assessment of the state of the processes and the state of the equipment of generators and loads; dynamic pricing and a dynamic assessment of the state of use of primary fuel and/or current costs of generators; economic efficiency of generator operation and loads; an assessment of environmental acceptability, in particular, the volume of CO₂ emissions; provides demand-side management, managing maximum energy consumption; a forecast of system development; an assessment of mutual flows of electricity; system resistance to disturbances; a forecast of metrological indicators, potential opportunities for generating RESs (wind power plants, solar power plants, etc.); an assessment of current costs; the state of electromagnetic compatibility of system elements and operation of electricity storage devices; and ensures work on local electricity markets. The application of smart monitoring in the formation of tariffs on local energy markets for transactive energy systems is shown by conducting a combined comprehensive assessment of the energy produced by each individual power source with graphs of the dependence of costs on the generated power. Algorithms for the comprehensive assessment of the cost of electricity production in a transactive system for calculating planned costs are developed, and the calculation of the cost of production per 1 kW is also presented. A visualization of the results of applying this algorithm is presented. Full article