Search Results (575)

In this work, we present an experimental validation of a modified Halbach array magnet configuration for passive electrodynamic suspension (EDS) systems. The study builds upon previous research that indicated improved lift-to-drag performance and reduced power consumption by altering the span (fill factor) of horizontally magnetised magnets in a Halbach array. A custom rotating test rig was developed to measure both magnetic field distributions and levitation/braking forces for several Halbach array configurations with varying magnet width ratios. Six magnet array packs were tested, featuring different fill factors (0.125, 0.5, 0.875), magnet lengths, and wavelengths. The experimental results show good agreement with 3D finite-element simulations across a range of speeds (0–85 m/s) and air gaps, confirming that non-classical Halbach arrays (with a fill factor ≠ of 0.5) can achieve higher energy efficiency. In particular, configurations with extreme fill factors produced lower magnetic drag for the same lift force, yielding a higher lift-to-drag ratio and a reduced magnetic friction coefficient. These findings validate the proposed modified Halbach arrangement and demonstrate that adjusting the horizontal magnet span can indeed reduce the power requirements of EDS maglev systems. The novelty of this work lies in the combined numerical–experimental assessment of mixed-length Halbach array configurations, revealing previously unreported scaling effects between magnet width ratio and force stability in short-stroke applications. Full article

Demagnetization faults in direct-drive permanent magnet synchronous motors (DDPMSM) can cause significant performance degradation and unplanned downtime. Traditional fault location methods, which rely on manual feature extraction, exhibit limited accuracy and efficiency in complex and variable operating conditions. To address these limitations, this study presents a demagnetization fault location method based on a search coil employing a data-driven one-dimensional convolutional neural network (1D-CNN). Firstly, the arrangement of search coils was determined, and a partitioned mathematical model was established, using the residual back electromotive force (back-EMF) of the search coil over a single electrical cycle as the fundamental unit. Secondly, the residual back-EMF in the search coil is analyzed under various demagnetization parameters and operating conditions to assess the robustness of the proposed method. Furthermore, a 1D-CNN-based fault location model was developed using residual back-EMF signals as the input and targeting the identification of demagnetized permanent magnet types. Simulation and experimental results demonstrate that the proposed method can effectively detect and locate demagnetization faults across different operating conditions. When the demagnetization degree is not less than 10%, the fault location accuracy reaches 99.58%, and the minimum detectable demagnetization degree is 8%. The approach demonstrates excellent robustness and generalization, offering an intelligent solution for demagnetization fault location in PMSMs. Full article

A spiral spin arrangement with a magnetic unit cell 28 times the size of the nuclear one has been reported for Fe spins below T_N = 80 K in bilayered van der Waals gapped FeOCl. In this work, we employ neutron magnetic diffraction and ac magnetic susceptibility to reveal a much smaller magnetic unit cell only 4 times the size of the nuclear one for Fe spins below T_N = 119 K, upon intercalation of 27% non-magnetic Na ions into the van der Waals gaps of FeOCl. X-ray emission spectra and X-ray absorption edge spectra reveal a charge transfer from the intercalated Na ions to the Fe sites, which partially reduces the Fe³⁺ into Fe²⁺ ions. The reduction results in a significantly increased Fe-O-Fe bond angle, which strongly enhances the antiferromagnetic superexchange (AFMSE) coupling relative to the competing ferromagnetic direct exchange (FMDE) coupling between neighboring Fe ions, thereby driving to a higher degree of magnetic symmetry and a substantially higher Neel temperature for the Fe spins in Na_0.27FeOCl. Full article

Liquid sloshing in partially filled tanks is commonly studied because of its influence on vehicle stability, structural loading, and control performance. In experimental investigations, sloshing measurements can be contaminated by mechanically induced fluid–structure interactions originating from the actuation system itself. This study presents a bench-scale experimental investigation of the interaction between static magnetic fields and the dynamic response of a mechanically excited water-tank system, with particular emphasis on distinguishing sloshing-related motion from higher-frequency mechanical effects. A rectangular acrylic tank was subjected to near-resonant horizontal excitation at a fixed fill height. A ferromagnetic steel plate was mounted externally beneath the tank and kept identical in all experiments, while either permanent magnets or mass-matched nonmagnetic dummies were attached externally to one sidewall. Two configurations were examined: a symmetric split-wall layout (15 + 15) magnets and a single-wall high-field arrangement with 30 magnets (Mag–30@L) together with its dummy control (Dummy–30@L). The center-of-gravity motion ${\mathrm{CG}}_y\left(t\right)$ was reconstructed from four load cells and analyzed in the time and frequency domains. Band-limited analysis of the primary sloshing mode near 0.55 Hz revealed no statistically significant influence of the magnetic field, indicating that static magnets do not measurably affect the fundamental sloshing dynamics under the present conditions. In contrast, a higher-frequency response component in the 10–20 Hz range, attributed to mechanically induced fluid–structure interaction associated with actuator reversal dynamics, was consistently attenuated when magnets were present; this component is absent in corresponding CFD simulations and is, therefore, not associated with sloshing motion. Given the extremely small magnetic Reynolds and Stuart numbers for water, the observations do not support any volumetric magnetohydrodynamic mechanism; instead, they demonstrate a modest magnetic influence on a mechanically excited, high-frequency coupled mode specific to the present experimental system. The study is intentionally limited to bench scale and provides a reproducible dataset that may inform future investigations of magnetically influenced fluid–structure interactions in experimental sloshing rigs. Full article

This study proposes a hybrid wireless power transfer (WPT) coupler that integrates a Double-D (DD) coil and a Split Capacitive Plate (SCP) for unmanned aerial vehicle (UAV) near-field charging stations. The proposed structure arranges the DD coil and SCP orthogonally in a stacked configuration, enabling simultaneous utilization of both magnetic and electric field coupling paths. The equivalent circuit is composed of integrated inductive and capacitive coupling branches. The overall network is divided into subcircuits to define transmission matrices, which are then converted into a 2 × 2 S-parameter matrix. To verify the analytical model, the equivalent circuit results were compared with 3D full-wave simulation outcomes, showing a discrepancy of less than 8%, which is acceptable considering circuit simplification and parasitic effects. Furthermore, simulation results under positional and rotational misalignment conditions confirm that the proposed coupler maintains stable power transfer efficiency even beyond a 25% offset range. These results demonstrate that the complementary coupling mechanism, where one dominant coupling mode compensates for the attenuation of the other, operates effectively under misalignment. Consequently, the proposed hybrid coupler provides a promising alternative for enhancing misalignment tolerance in UAV near-field wireless charging systems. Full article

Two diruthenium(II,II) naphthyridine complexes coordinated with 4-trifluoromethylbenzoate (O₂CPh-4-CF₃) and 3,5-bis(trifluoromethyl)benzoate (O₂CPh-3,5-diCF₃) ligands, formulated as [Ru₂(npc)₂(O₂CPh-4-CF₃)₂] (4; npc = 1,8-naphthyridine-2-carboxylate) and [Ru₂(npc)₂(O₂CPh-3,5-diCF₃)₂] (5), respectively, were synthesized and structurally characterized. Single-crystal X-ray diffraction analysis revealed that both 4 and 5 form a direct metal–metal bond between the two Ru ions (2.2893(8) and 2.2896(7) Å, respectively) and adopt a paddlewheel-type structure in which two npc and two trifluoromethyl-substituted benzoate ligands are coordinated to a Ru₂⁴⁺ core with a cis-2:2 arrangement. The temperature dependence of the magnetic susceptibility measurements of 4 and 5 exhibited very large zero-field splitting (D = 242 and 246 cm⁻¹, respectively) of the triplet ground state of the Ru₂⁴⁺ core, similar to that of [Ru₂(npc)₂(O₂CPh)₂] (3; D = 238 cm⁻¹). Owing to the effects of the trifluoromethyl substituents, compared with 3, 4 and 5 showed (i) a significant blue shift of the absorption bands in the visible region and (ii) a positive shift of the redox potentials, with both shifts becoming more pronounced as the number of trifluoromethyl substituents increased. These experimental results are in good agreement with the electronic structure results obtained from density functional theory calculations. Full article

Owing to their dimensions and high aspect ratio, magnetic nanowires possess distinctive physical and chemical properties and are of great importance in building nanoelectronics devices. Nanowires are traditionally produced by electrochemical deposition methods using alumina or polycarbonate membranes, and their parameters (porosity, size, and arrangement of pores) strongly influence the magnetic properties of nanowires. However, very often, the effect that cannot be neglected during synthesis is overdeposition. The influence of overdeposition on the magnetic properties of nanowires is often overlooked, but it can strongly alter the magnetic behavior of the system. In this study, we use micromagnetic simulations to investigate how different levels of overdeposition affect the hysteretic behavior of nanowires and their magnetization switching mechanism. It was shown that the formation of hemispherical caps on the ends of the nanowires may alter the out-of-plane magnetic anisotropy of the nanowires and strongly influence the squareness of the hysteresis loop. The demagnetizing field distribution for nanowires with overdeposition was also investigated, showing a strong influence of its spatial distribution change on the reversal mechanism and interaction between nanowires. The obtained results were compared to existing experimental observations, showing good agreement with the magnetic behavior of the system. Performed research can be of great interest to experimental groups, as it highlights the importance of controlling overdeposition during nanowire synthesis and its potential influence on magnetic performance. Full article

Additive manufacturing technologies are characterised by the capability to produce components with complex geometries that are difficult to achieve using conventional methods. Despite the wide range of available materials and additive manufacturing processes, fulfilling design requirements related to surface structure parameters remains a considerable challenge. This paper presents the findings of an investigation into the influence of abrasive treatment of a ferromagnetic fluid on the surface roughness of MEX-printed samples. The samples were fabricated using TPU 95A material. The abrasive medium employed in the study comprised carbonyl iron and silicon carbide. A dedicated tool was designed for the experiments, incorporating neodymium magnets arranged in four asymmetrically distributed slots. The proposed tool represents an unconventional approach in comparison with existing practices. Tests were conducted in three measurement series—B, C, and D—while series A served as the control group. Analysis of the experimental results revealed that, for the parameters Sp (height of the highest apex) and Sz (maximum height, defined as the sum of Sp and Sv, representing the height of the highest apex and the maximum pit depth, respectively), the most significant reduction in parameter values was observed for series D. Full article

The consequent-pole interior permanent-magnet (CPM) motor is a promising alternative for minimizing rare-earth magnet usage while supporting high-speed operation. However, rotor flux asymmetry often leads to distorted back-electromotive force waveforms and increased torque ripple. This study investigated a flared-type CPM motor that employs ferrite magnets arranged in a flared configuration to enhance flux concentration within a compact rotor. To address waveform distortion, structural modifications such as bridge removal and an asymmetric air-gap design were implemented. Three rotor parameters—polar angle, asymmetric air-gap length, and rotor opening length—were optimized using Latin hypercube sampling combined with an evolutionary algorithm. Finite element method analyses conducted under no-load and rated-load conditions showed that the optimized model achieved a 77.8% reduction in torque ripple, a 43.4% decrease in cogging torque, and a 0.5% improvement in efficiency compared with the basic model. Stress analyses were performed to examine the structural bonding strength and rotor deformation of the optimized model under high-speed operation. The results revealed a 5.5× safety margin at four times the rated speed. The proposed approach offers a cost-effective and sustainable alternative to rare-earth magnet machines for high-efficiency household appliances, where vibration reduction, cost stability, and energy efficiency are critical. Full article

The aim of the manuscript is to analyze the influence of the magnetic orientation of steel microfibers (length 13 mm, diameter 0.2 mm) on the mechanical properties and fracture propagation of cementitious composites. The series varied in terms of the volumetric content of the fibers, 0%, 1% and 2% (V_f), and the orientation variant, random (S) or magnetic (S-M, B = 80 mT). Three-point bending tests were performed with force-deflection curve (F-δ) registration. The flexural tensile strength (f_ct,fl), the flexural elastic modulus (E_f), the work of fracture up to a specified residual load level (W_f) and deflection level (W_f*), as well as the compressive strength (f_c) were determined. The improvement of the mechanical properties was noted for magnetically oriented fibers in reference to random arrangement (f_ct,fl: 90–133%; f_c: 12–34%; W_f*: 98–146%). The efficiency factor (η_X) was introduced to determine the change in property per fiber content unit, which enabled comparison regardless of the fiber dosage. As the higher η_X values were determined for 1% content (e.g., f_ct,fl equal to 133%/p.p for V_f = 1% and 45%/p.p for V_f = 2%), further increase in dosage was expected to cause reduced improvement. Different fracture mechanisms were noted for S and S-M composites by means of the Digital Image Correlation method. Full article

Aromaticity tuning of biaryl monophosphines can significantly impact their catalytic performance. Biaryl monophosphines constitute a crucial class of compounds due to their potential as ligand precursors in asymmetric Pd-catalyzed cross-coupling and some other catalytic reactions. In this study, we investigate the tuning of aromaticity within a series of selected biaryl monophosphine derivatives exhibiting diverse steric and electronic properties. XRD structures and Hirshfeld surface analyses were complemented by DFT calculations. Aromaticity indices, such as geometric HOMA, HOMER, and magnetic NICS, were evaluated and correlated with ligand properties. NICS(1)zz was the most sensitive to aromaticity changes. The results showed that among the ring-activating substituents, methoxy groups were more beneficial than hydroxy ones. The hydroxy groups not only modulated the aromaticity but also induced unfavorable conformational changes of the catalyst precursors through strong inter- and intramolecular hydrogen bonding. The spatial arrangement of the P atom adjacent to the aryl ring system confers catalytic advantages by promoting the assembly of coordination compounds (catalysts) in which Pd—C bond formation occurs, yielding C,P-chelated five-membered palladacyclic structures. The hydroxy substituents blocked access to the P atom, thereby hindering catalytic performance. The studies show that even subtle changes in the monophosphine biaryl scaffold, especially aromaticity tuning should be carefully evaluated during the rational design of new efficient catalysts. The studied compounds were evaluated for their biological activity against three Gram-positive and four Gram-negative bacteria as model microorganisms. The research was supplemented by in vitro cytotoxicity evaluation. Full article

We experimentally investigate the structural, magnetic, transport, and electronic properties of two d⁵ iridate double perovskite materials La₂BIrO₆ (B = Mg, Zn). Notably, despite similar crystallographic structure, the two compounds show distinctly different magnetic behaviors. The M = Mg compound shows an antiferromagnetic-like linear field-dependent isothermal magnetization below its transition temperature, whereas the M = Zn counterpart displays a clear hysteresis loop followed by a noticeable coercive field, indicative of ferromagnetic components arising from a non-collinear Ir spin arrangement. The local structure studies authenticate perceptible M/Ir antisite disorder in both systems, which complicates the magnetic exchange interaction scenario by introducing Ir-O-Ir superexchange pathways in addition to the nominal Ir-O-B-O-Ir super-superexchange interactions expected for an ideally ordered structure. While spin–orbit coupling (SOC) plays a crucial role in establishing insulating behavior for both these compounds, the rotational and tilting distortions of the IrO₆ (and MO₆) octahedral units further lift the ideal cubic symmetry. Finally, by measuring the Ir-L₃ edge resonant inelastic X-ray scattering (RIXS) spectra for both the compounds, giving evidence of spin–orbit-derived low-energy inter-J-state (intra t_2g) transitions (below ~1 eV), the charge transfer (O 2p → Ir 5d), and the crystal field (Ir t_2g → e_g) excitations, we put forward a qualitative argument for the interplay among effective SOC, non-cubic crystal field, and intersite hopping in these two compounds. Full article

This research prepared and characterised novel mixed coordination complexes derived from escitalopram with eugenol and curcumin to form (L₁) and (L₂), respectively. The complexes were prepared via Williamson ether synthesis and analysed by FTIR, UV–Vis, ¹H-NMR spectroscopy, elemental analysis, molar conductivity, and magnetic susceptibility. The results confirmed their octahedral geometries. Magnetic investigation reported high-spin configurations for Mn(II), Co(II), and Ni(II) complexes, whereas Cu(II) exhibited a distorted octahedral arrangement with characteristic d–d transitions. In addition, the calculation of Density functional theory (DFT) provided more insight into the detailed structural and electronic properties of the new ligand and its complexes. Antimicrobial compounds were evaluated against Escherichia coli, Staphylococcus aureus, and Candida albicans through the agar well diffusion method. The reported results revealed that Cobalt complexes showed antimicrobial activity followed by Copper (Cu), Nickel (Ni) and Manganese(Mn) complexes, respectively, due to an increase in Co-lipophilicity, which leads to improved diffusion through microbial cell membranes. The research findings confirmed that escitalopram-based mixed ligands coordinate with transition metals and could have significant biological applications. Full article

The integration of miniaturized magnetometers with Unmanned Aerial Vehicles (UAVs) has revolutionized magnetic surveying, offering flexible, high-resolution, and cost-effective solutions for geophysical applications also in remote areas. This study presents a comparative analysis of two configurations using UAV-borne scalar magnetometers through several surveys conducted in the Altopiano di Verteglia (Southern Italy), chosen as a test-site since buried pipes are present. The two systems differ significantly in sensor–platform arrangement, noise sensitivity, and flight configuration. Specifically, the first employs the MagNimbus magnetometer with two sensors rigidly attached on two masts at fixed distances, respectively, above and below the UAV, enabling the vertical gradient estimation while increasing noise due to proximity to the platform. The second involves the use of the MagArrow magnetometer suspended at 3 m below the UAV through non-rigid ropes, which benefits from minimal electromagnetic interference but suffers from oscillation-related instability. The retrieved magnetic anomaly maps effectively indicate the location and orientation of buried pipes within the studied area. Our comparative analysis emphasizes the trade-offs between the two systems: the MagNimbus-based configuration offers greater stability and operational efficiency, whereas the MagArrow-based one provides cleaner signals, which deteriorate with the vertical gradient computation. This work underscores the need to optimize UAV-magnetometer configurations based on environmental, operational, and survey-specific constraints to maximize data quality in drone-borne magnetic investigations. Full article