Search Results (504)

This study aims to develop sustainable conductive nanocomposites based on poly(lactic acid) (PLA)/poly(ε-caprolactone) (PCL) blends reinforced with multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (G), focusing on their multifunctional performance. The novelty lies in the production of hybrid nanocomposites based on PLA/PCL blends with MWCNT/G using conventional industrial processing techniques, enabling the development of eco-friendly nanocomposites with tailored electrical, mechanical, and electromagnetic properties. The nanocomposites were prepared by twin-screw extrusion followed by injection molding. Rheological, scanning electron microscopy (SEM), mechanical, thermal, thermomechanical, electrical conductivity, and electromagnetic shielding properties were systematically evaluated. From a rheological perspective, the PLA/PCL/MWCNT and PLA/PCL/MWCNT/G nanocomposites exhibited a plateau at low frequencies, associated with the formation of a percolated network. This was confirmed by the significant increase in electrical conductivity and electromagnetic shielding response. The morphology observed by SEM showed a refinement of the PCL phase in the PLA matrix with the incorporation of MWCNT. The PLA/PCL/MWCNT/G (4/2 parts per hundred resin, phr) nanocomposite showed a 309% increase in impact strength compared to neat PLA, while maintaining the heat deflection temperature (HDT). The elastic modulus exceeded 2300 MPa and accelerated the crystallization process by more than 15 °C compared to PLA, which makes it important to reduce injection molding time. Additionally, it exhibited the highest electrical conductivity level, around 6.79 × 10⁻⁵ S/cm, which resulted in improved electromagnetic shielding performance in the 8.2–18 GHz range, highlighting the synergistic effect between 1D and 2D fillers. The developed PLA/PCL/MWCNT and PLA/PCL/MWCNT/G nanocomposites demonstrate potential for antistatic applications, combining sustainability with multifunctional performance and industrial scalability. Full article

The Zeta-Minimizer Theorem (ZMT) provides a complete deductive unification of statistical mechanics, number theory, helical geometry, thermodynamics, and electromagnetism from three primitive axioms alone. Starting with the non-proper Archimedean conical helix and the explicit covariant fugacity Hessian, the universal grand-partition function Z(s) is constructed via the integer-gear rule. This functorially invariant object yields gear occupations, Lyapunov exponents, and interaction parameters that govern all subsequent results. Interface matching and marginal stability λ_2,19 (x_2) = 0 trigger superconductivity at solid–fluid boundaries, while the categorical invariance of Z(s) produces exact magnetic and electric equilibrium curves. The Variational Reaction Rate Theorem then projects the framework onto dynamics, yielding Maxwell’s equations, demystified electrical units as helical torque quantities, and a complete classification of electronic phases. Phonons, Cooper pairing, the superconducting gap, and the full BCS correspondence follow without additional postulates. The same marginal-stability condition reproduces the Casimir effect, the Quantum Hall effect, and the entire 115-year experimental history of superconductivity. Generalization of interface matching to arbitrary solid–liquid pairs and introduction of Variational Anchor Cancellation (VAC) self-organizes a shielded superconducting layer. Finally, the first-principles engineering blueprint of the Radial Helical Gear Condenser (RHGC) delivers a modular, self-regulating device that engineers superconductivity at ambient or near-ambient temperature using only a radial pressure gradient and existing pipeline technology. All predictions are zero-parameter and fully deducible from the three axioms. Full article

Carbon nanotubes (CNT) are among the strongest candidates for electromagnetic interference (EMI) shielding materials because of their excellent performance. However, when assembled into macroscale materials, their conductivity is usually limited to 10⁴ S/m, restricting further application as shielding materials. Here, we prepared a carbon nanotube composite film (Au/Cl-CNT) with high conductivity and excellent EMI properties. Characterizations confirm that Au exists in the form of uniform Au plates and particles anchored on the CNT surface, while Cl is doped into the CNT framework as halogen dopants. The optimized Au/Cl-CNT film delivers an ultra-high electrical conductivity of 3.39 × 10⁵ S/m, which is approximately 23 times higher than that of the pristine CNT film. The excellent electrical properties of the Au/Cl-CNT films endow them with excellent EMI shielding effectiveness (SE). Au/Cl-CNT films with a thickness of ~10.5 μm achieve an EMI SE of up to 67 dB across both the X-band and Ku-band. The superior EMI SE mainly results from the combined effect of various mechanisms, namely reflection inside and outside the material, as well as absorption inside the material. This work clarifies the synergistic enhancement mechanism of Au and Cl on CNT conductivity and EMI shielding, offering new insights into halogen-modified shielding materials. Full article

With the rapid development of wireless communications, electromagnetic interference (EMI) in complex environments has become a critical factor affecting communication quality. Addressing the EMI issues caused by multi-band coexistence in indoor scenarios, traditional metallic resonant structures, while effective in filtering, often compromise optical transparency due to light blockage. To resolve this trade-off, this paper proposes a dual-ring resonant frequency-selective surface (FSS) based on Indium Tin Oxide (ITO) films. This design aims to achieve efficient transmission in specific C-band frequencies and suppress out-of-band interference, realizing excellent optical transmittance while ensuring electromagnetic shielding effectiveness. The designed metasurface targets a passband of 5.35–5.40 GHz for sub-6 GHz indoor communications. Experimental results confirm superior transmission in this range and significant out-of-band suppression. Furthermore, featuring high optical transparency, the structure can be directly integrated onto glass surfaces. It is not only suitable for optically transparent devices but also provides a compact passive solution for anti-EMI applications in smart buildings and sub-6 GHz indoor communications. Full article

Flexible transparent conductive films (TCFs) and their applications have attracted extensive interest. Silver nanowires (AgNWs) have been explored to replace conventional indium tin oxide (ITO) due to their high optical transmittance and superior electrical conductivity. Nevertheless, AgNWs tend to oxidize under ambient conditions, which weakens the conductive network and limits long-term performance. Spraying reduced graphene oxide (rGO) can stabilize the conductive network and inhibit oxidation, thereby enhancing the overall properties of the films. In this work, rGO/AgNW/PET TCFs were prepared using a spray-coating approach. The transmittance of the rGO/AgNW/PET TCFs was measured at 77% at 550 nm, accompanied by a sheet resistance of 6.8 Ω/sq. The films achieved the surface temperature of 95 °C at 6 V with stable operation while also achieving an electromagnetic interference shielding effectiveness of 27 dB. This structural design improves both performance and stability, offering great potential for flexible TCFs in advanced optoelectronic applications. Full article

To improve the durability of terahertz (THz) electromagnetic shielding materials in atomic oxygen environments relevant to low Earth orbit (LEO), two MXene/para-aramid nanofiber (ANF) composite architectures were designed, including a uniformly blended structure and a sandwich configuration. Ti₃C₂T_x MXene was used as the conductive phase, while ANF served as a protective matrix. Oxygen plasma treatment was employed to simulate atomic oxygen exposure. The results show that the plasma resistance of blended films strongly depends on MXene content. Increasing the MXene fraction enhances conductive network redundancy and reduces conductivity degradation. In contrast, the sandwich-structured film exhibits superior structural stability. The outer ANF layers effectively limit direct plasma–MXene interaction and undergo surface carbonization during plasma exposure, forming an additional diffusion barrier. As a result, the sandwich film maintains stable THz shielding performance, with the average shielding effectiveness increasing from 42.6 dB to 44.9 dB after plasma treatment. These results indicate that structural regulation of the internal conductive network, which limits plasma penetration, is essential for maintaining stable MXene-based THz shielding performance under oxidative plasma conditions. Full article

To mitigate safety risks such as tunnel collapse and water inrush induced by fault fracture zones during urban shield tunneling, this study investigates the application mechanisms and identification characteristics of the surface transient electromagnetic (TEM) method for ahead-of-face geological prediction, using a shallow metro tunnel (30–50 m burial depth) in Qingdao as a case study. Departing from conventional empirical threshold approaches, a three-dimensional geological model incorporating a fault fracture zone is constructed. Guided by electromagnetic diffusion theory, the transient field response evolution is numerically simulated to obtain time-domain electromagnetic decay curves at various observation points. By integrating these simulations with field measurements, quantitative criteria for fault identification are extracted. The results demonstrate that the electric field response attenuation rate at measurement points directly overlying the fault fracture zone is significantly faster than that in the intact host rock. This accelerated decay behavior is jointly governed by the fault scale, degree of water saturation in the fracture zone, and source–receiver offset, serving as a primary indicator for fault identification. In the apparent resistivity profiles, the fault-intersecting zones exhibit distinct abrupt transitions between low and high resistivity. The water-saturated fracture zone manifests as a well-defined low-resistivity anomaly, generating a pronounced electrical contrast with the high-resistivity host rock. Field validation confirms that the identified low-resistivity anomaly aligns closely with the actual location of the water-bearing fault, which was subsequently verified during tunnel excavation. This study elucidates the physical mechanism of electromagnetic diffusion distortion induced by faults under shallow urban conditions. The proposed integrated criterion, combining the response attenuation rate with abrupt apparent resistivity boundaries, effectively mitigates the non-uniqueness inherent in single-parameter geophysical interpretations. These findings provide theoretical support and a reproducible engineering criterion for ahead-of-face fault prediction in metro tunnels. Future research should further incorporate the effects of geological anisotropy and dynamic groundwater seepage on the electromagnetic diffusion process. Full article

A pressing challenge of modern wireless networks is ensuring stable radio coverage inside buildings, where radio signal propagation is significantly complicated by the influence of building structures. Reinforced concrete walls, floor slabs, internal partitions, and energy-efficient windows with metallized coatings create substantial obstacles to the propagation of electromagnetic waves, causing reflection, absorption, and scattering. As a result, areas with weakened coverage are formed inside buildings, leading to deterioration in mobile communication quality and reduced data transmission rates. This study presents an experimental investigation of the received signal strength of mobile operators inside a multi-storey residential complex. An analysis was conducted to evaluate the impact of building height, architectural features, and construction materials on radio signal propagation. In addition, the frequency bands used in 4G LTE and 5G networks by mobile operators were examined. It was found that LTE networks mainly operate in the 1.8–2.1 GHz frequency range, whereas 5G networks operate in the n77 band (3.6–3.7 GHz), which provides higher data throughput but is characterized by greater signal attenuation when propagating inside buildings. To address this issue, a Distributed Antenna System (DAS) based on GPON technology was implemented in the studied building. The placement of antenna equipment on the roof enabled the efficient reception of the signal from the base station and its subsequent distribution inside the building through an internal antenna network. The measurement results demonstrated that the deployment of a GPON-based DAS significantly improves the received signal level and ensures more uniform radio coverage inside indoor environments. The obtained results confirm that the use of distributed antenna systems is an effective solution for compensating signal losses caused by the shielding effect of building structures and can significantly improve the quality of mobile communications in dense urban environments. The results show that the RSRP level in indoor environments without DAS decreases to approximately −100 to −110 dBm, while after deployment of the GPON-based DAS, it improves to −45 to −75 dBm. This corresponds to a signal gain of up to 40–50 dB, ensuring stable connectivity and significantly improved data transmission performance. Full article

Background: Optically pumped magnetometers (OPMs) have emerged as a promising technology for neuromagnetic recording in humans. Current state-of-the-art OPM systems are housed in large magnetically shielded rooms to reduce external electromagnetic noise and typically comprise sensor arrays covering the entire head. Such systems are extremely costly to purchase and install, and take up large amounts of physical space, which limits the accessibility of this technology to research groups with limited funding. Here we sought to evaluate the utility of a more accessible “starter” OPM system comprising a small cylindrical mu-metal shield and partial sensor coverage. Methods: Twelve participants underwent right-sided median nerve stimulation (MNS) intended to elicit ubiquitous sensorimotor responses: somatosensory-evoked fields (SEFs, comprising N20m, P35m and P60m components) and event-related (de)synchronization (ERD/ERS) of oscillatory neuronal rhythms in the mu and beta frequency ranges. Results: Following MNS, we observed robust N20m and P60m peaks, as well as the expected mu ERD and beta ERS effects. Moreover, these responses could be localized to expected cortical generators. However, we observed markedly lower SNR than that seen in state-of-the-art systems. We make recommendations for further improvements to this system and others like it. Full article

Conventional memory machines often suffer from magnetic interference between high-coercive-force (HCF) and low-coercive-force (LCF) permanent magnets, which unintentionally alters the magnetization state and limits overload capability. To address this challenge, this paper proposes a novel axial parallel memory machine (DCB-AXMM) featuring a DC-bias-controlled variable-flux capability. Instead of a conventional structure, the proposed machine employs an axially segmented topology to spatially isolate the excitation sources, effectively shielding the LCF PMs from HCF PM interference and armature reaction. Furthermore, integrated windings are utilized to perform both armature excitation and pulse magnetization, thereby enhancing the overall space utilization. The flux-regulating mechanism is theoretically elucidated using a piecewise linear hysteresis model. To maximize electromagnetic performance, a two-step optimization framework based on a genetic algorithm (GA) is implemented. Comprehensive non-linear finite element analysis (FEA) is conducted to validate the proposed design. Quantitative results demonstrate that the DCB-AXMM achieves a wide flux regulation range, characterized by a 21.8% average torque reduction from 2.2 Nm at full magnetization to 1.72 Nm at zero magnetization, while maintaining a robust 1.5-times overload capability. These measurable outcomes confirm the topology’s effectiveness and reliability for high-performance variable-flux applications. Full article

The intense low-frequency magnetic field generated by the Electromagnetic Aircraft Launch System (EMALS) during operation poses a serious EMI threat to electronic equipment within carrier-based aircraft nacelles. To address this, a three-dimensional transient finite element model of a long-primary double-sided linear induction motor is established. Using a quasi-static equivalent method, the 118 Hz magnetic field distribution inside and outside a typical engine nacelle is characterized. Results indicate that due to the skin depth significantly exceeding material thickness, the eddy-current shielding of the aluminum alloy nacelle is inadequate, producing internal field intensities that far exceed standard limits and directly threaten sensitive onboard electronics. Based on the magnetic shunting principle, a composite shielding strategy is proposed: applying a flexible high-permeability coating on the nacelle surface to attenuate the overall field, supplemented by local permalloy shields for core equipment. Simulation verification demonstrates that this approach reduces the internal field to safe levels. It achieves effective shielding performance while balancing engineering feasibility with lightweight requirements, providing a viable pathway for ensuring the reliable protection of carrier-based aircraft in intense electromagnetic environments. Full article

To address the severe shielding of conventional electromagnetic signals by metallic pipelines and the inherent design trade-off under fixed-voltage excitation, whereby increasing coil size suppresses current and limits magnetic field intensity, this study proposes an independently parallel-fed multistage coil enhancement scheme for the transmitter of through-wall magnetic induction communication. Based on electromagnetic theory and COMSOL6.3 simulations, a coupled analysis framework for multistage coils was established to systematically evaluate the effects of axial partitioning, radial partitioning, nonuniform turn allocation, and magnetic-core loading on branch-current amplitude and phase consistency as well as spatial magnetic field intensity. The results show that, under in-phase, equal-frequency excitation, the resultant magnetic field intensity increases approximately linearly with the number of partitions. The partition scheme significantly alters the mutual inductance distribution among sub-coils, thereby affecting current synchronization and magnetic field synthesis efficiency. The introduction of a high-permeability magnetic core markedly improves the amplitude and phase consistency of the radially partitioned structure and enhances output stability. Considering magnetic field output, current synchronization, and engineering feasibility, the axial–radial hybrid four-partition structure with a magnetic core was identified as the preferred configuration. These findings provide a theoretical basis and structural guidance for transmitter design in low-frequency through-wall magnetic induction communication under metallic shielding conditions. Full article

Constructing efficient conductive networks in flexible polymer matrices remains a central challenge in electromagnetic interference (EMI) shielding material design. In this work, a ‘point-line’ hybrid filler system combining conductive carbon black (CB) and multi-walled carbon nanotubes (MWCNTs) was incorporated into a silicone rubber matrix to systematically engineer the conductive network architecture. By optimising the CB/MWCNT blending ratio, a composite with a tensile strength of 8.5 MPa, elongation at break of 180%, and EMI shielding effectiveness of 50 dB was achieved at a 1:1 weight ratio. Further surface modification of the hybrid fillers using five surfactants, including sodium dodecylbenzene sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), polyvinylpyrrolidone (PVP), nonylphenol ethoxylate (NPEO), and octylphenol ethoxylate (OPEO), was systematically investigated. OPEO modification was proved the most effective, improving EMI shielding performance to 58 dB while enhancing tensile strength by 11.8% and elongation at break by 50%. These results demonstrate that rational filler hybridisation combined with targeted surfactant modification offers a practical and scalable route to high-performance flexible EMI shielding composites. Full article

Functional nanocomposites have emerged as a transformative class of materials for advanced energy and electronic applications due to their ability to integrate multiple functionalities within engineered nanoscale architectures. This review provides a comprehensive analysis of the fundamental principles governing nanocomposite behavior, including classification frameworks, commonly employed nanofillers, and critical structure–property relationships. Emphasis is placed on interfacial interactions, dispersion quality, percolation phenomena, and anisotropic effects that dictate electrical, thermal, mechanical, and electrochemical performance. State-of-the-art synthesis and fabrication strategies—ranging from solution-based and melt-processing techniques to vapor-phase deposition and additive manufacturing—are systematically examined in relation to microstructural control and scalability. The multifunctional properties of nanocomposites are critically evaluated, highlighting their relevance in energy storage systems, energy conversion technologies, flexible electronics, sensors, and electromagnetic interference shielding. Key challenges, including nanofiller agglomeration, interfacial compatibility, long-term stability, cost, and sustainability considerations, are discussed alongside emerging solutions. Finally, future perspectives focusing on next-generation nanofillers, AI-assisted materials design, and sustainable manufacturing pathways are outlined, providing a roadmap for the rational development and industrial translation of high-performance multifunctional nanocomposites. The scope of this review is deliberately focused on materials-level structure–process–property relationships in functional nanocomposites, rather than on detailed device-level electronic design or application-specific electromechanical implementations. Full article

External stray magnetic fields from permanent magnet synchronous motors (PMSMs) may cause electromagnetic interference to nearby equipment and limit their application in space-constrained systems. To address this issue, this paper investigates the use of laminated Co-based amorphous ribbon shields for stray-field suppression. An efficient equivalent modeling method is proposed for the simulation of such multilayer thin shielding structures, in which the laminated shield is replaced by an equivalent single-layer model while preserving its macroscopic shielding behavior. The method is first assessed in 2-D through comparisons between refined laminated and simplified equivalent models under both linear permeability and nonlinear magnetization-curve descriptions, and is then extended to 3-D PMSM shielding analysis under static and rotating no-load conditions with experimental validation. Results show that the 10-layer amorphous ribbon shield, with a total thickness of 420 μm, achieves a maximum shielding effectiveness of 7.9 dB at a measurement distance of two motor radii. The maximum deviation between simulation and experiment is 7.4%, and the equivalent model reduces computation time by 28% relative to the refined model. This method provides an accurate and efficient approach for the analysis and design of compact low-frequency magnetic shields for PMSMs. Full article