Search Results (119)

This paper investigates how the number of receiving coils in the Vertical Coil (VC) configuration affects energy transfer efficiency in Dynamic Wireless Power Transfer (DWPT) systems for electric vehicles (EVs). Building on our previous work, in which the VC design outperformed horizontally oriented DDQ coils, receiver arrays of three to seven coils were compared using a coupled finite element and circuit co-simulation at 85 kHz across a 30 cm air gap over a 3 m pass. The relationship between coil count and harvested energy proves to be non-monotonic. Increasing the count from three to five raises the peak efficiency from approximately 85% to above 90%, and extends the high-efficiency region from roughly $\left|x\right|\lesssim 0.9$ m to the full width of the pass through the appearance of secondary peaks. Beyond five coils the spacing between neighbouring receivers narrows, mutual inductance grows, the resonant branches detune, and the harvested energy per pass falls for both the six- and seven-coil arrays. The five-coil configuration therefore maximizes the energy harvested per pass for this geometry, and the work provides simulation-based design guidelines for the VC architecture. Full article

To address dependence on external power and the limited capability of conventional hydroelectric units to detect low-amplitude vibrations, this work introduces a self-contained, highly accurate monitoring device. The design incorporates a magnetically levitated configuration, with triboelectric films placed on both the upper and lower faces of the floating magnet. Under minor oscillations, magnetic repulsion increases the relative displacement between the friction layers, producing a substantial voltage that permits low-level vibration sensing. A surrounding induction coil responds to the levitated pole’s vertical motion; this motion intersects the magnetic flux, generating a current that provides stable energy for wireless data transmission. Experimental outcomes confirm a detection limit of 0.1 mm. At an amplitude of 1 mm and a load of 1000 Ω, the system achieves a maximum output of 9 mW and a power density of 1.587 W/m², ensuring reliable power. This configuration provides a new pathway for monitoring vibrations in hydroelectric turbine generators. Full article

High-resolution vertical profile observations of ocean environmental parameters are essential for investigating mesoscale ocean dynamic phenomena, such as internal waves, mesoscale eddies, and oceanic fronts. At present, vertical profile measurement in marine surveys mainly relies on shipborne winches to deploy and recover marine sensors, which entails high labor costs and considerable energy consumption. Unmanned observation platforms integrated with winch systems enable automatic sensor deployment and recovery, offering a viable approach to cutting observation costs. Nevertheless, inadequate energy supply remains a critical bottleneck restricting the large-scale popularization and application of such equipment. Accordingly, the development of high-efficiency winch systems tailored for unmanned autonomous observation platforms is of great engineering significance for facilitating long-term, continuous, and low-energy marine profile observation. This paper proposes a novel energy-saving winch with an embedded three-stage parallel nested energy storage structure for unmanned marine observation platforms. During operation, the coil spring energy storage system is charged during cable payout, and the stored elastic potential energy is released to assist motor driving in the cable retraction process. This auxiliary driving mode reduces motor power demand and improves the overall energy utilization efficiency of the platform. Experimental results demonstrate that, neglecting ocean current resistance, the proposed winch reduces energy consumption by 5% during cable payout and 21% during cable retraction. The overall energy consumption is decreased by 13% throughout a complete vertical profile measurement cycle. Under constrained and fixed energy supply conditions, this technology substantially enhances the sampling capability of unmanned marine platforms for ocean environmental monitoring. It further improves operational efficiency and extends continuous service time, providing key technical support for revealing ocean dynamic evolution and clarifying the formation and driving mechanisms of marine environmental phenomena. Full article

To address the issue of traditional bistable vibration energy harvesters (BVEHs) being prone to becoming trapped in a single potential well—which results in a narrowed energy harvesting bandwidth and reduced efficiency—this paper proposes a method that utilizes the nonlinear electromagnetic force generated during the induction process to modulate the kinematic behavior of the oscillator. The characteristics and influencing factors of the nonlinear force produced during electromagnetic induction are analyzed. A dual-cantilever beam structure is designed, with an iron-core coil and a magnet placed at the respective free ends. A mathematical model of a piezoelectric–electromagnetic coupled bimodal broadband vibration energy harvester is established and numerically simulated. Furthermore, a vertical vibration experimental platform is constructed to conduct frequency sweep tests. The experimental results demonstrate that the proposed piezoelectric–electromagnetic coupled bimodal broadband vibration energy harvester effectively improves energy harvesting efficiency. Within the frequency range of 5–20 Hz, the system exhibits two vibration modes, with resonant frequencies of approximately 7.7 Hz and 15.7 Hz. For a single-layer PVDF piezoelectric film, the maximum output power at the first and second resonance points is 8.9 μW and 9.7 μW, respectively. The electromagnetic module achieves maximum output powers of 0.39 W and 0.71 W. Moreover, within the frequency ranges of 6.3–9.8 Hz and 14–17.7 Hz (a total bandwidth of 7.2 Hz), the device maintains a stable power output. The effective bandwidth is broadened by approximately 80%, demonstrating excellent broadband performance. Full article

This paper presents the design, prototype realization, and experimental validation of an inductive wireless power transfer (WPT) platform for static charging of electric vehicles. The study integrates magnetic-coupler design, resonant power-stage realization, and occupied-area magnetic-field assessment within a prototype-oriented engineering framework. The realized Tx/Rx magnetic assembly has dimensions of approximately 700 × 800 × 60 mm per coil, an inductance of about 60 μH, a coupling factor of about 0.45, and estimated coil losses of around 2%. The proposed system belongs to the 35 kW class, while the realized prototype was experimentally validated at a nominal 30 kW operating level, with peak capability up to 45 kW for 1 min. Experimental evaluation was carried out for air gaps up to about 100 mm, with measured transfer efficiency in the range 80–92% and favorable operation around 30 kW and a vertical air gap of approximately 70 mm. Representative occupied-area magnetic-flux-density measurements remained below the adopted 27 μT reference level under the reported operating conditions. The results confirm the practical feasibility of the proposed static EV charging platform and support its engineering relevance for high-power inductive charging applications. Possible extension toward on-route charging is discussed only as future work. Full article

Triaxial induction logging is particularly outstanding in identifying reservoir parameters including anisotropic strata, inclined boreholes and horizontal wells. However, the coplanar systems follow the traditional induction method of using a shielding coil to offset the direct coupling. This method results in severe horns in the coplanar coil response, which makes it more difficult to evaluate the water (oil) saturation of the reservoir. In this study, we used an analytic method to derive the magnetic field in a finite-thickness anisotropic medium by applying tangential continuity of the electric and magnetic field strengths, introducing the magnetic vector potential and Bessel functions. The response model influenced by different parameters was established. Under the same environmental parameters, the measurement range of the vertical and horizontal conductivities was larger than that of the traditional coplanar system. The apparent conductivity of the target layer was closer to the true value of the vertical conductivity in the layered strata, with an accuracy improvement of 78.9%. Furthermore, the improved coplanar system mechanism was revealed by analyzing the spatial distributions of eddy currents and the magnitudes of the magnetic fields generated. Finally, we designed an experimental device for a coplanar sensing system. Under the same parameters, the received signals of the improved coplanar system were greater than those of the traditional coplanar system in the air, which laid a foundation for the quantitative evaluation of stratigraphic anisotropy response characterization and inversion. Full article

Identifying primary ceramic forming techniques is often problematic when surface traces are altered or erased by secondary shaping on the potter’s wheel, particularly in vessels combining hand-building and wheel use. This study aims to develop a quantitative, non-destructive method to distinguish wheel-throwing and wheel-coiling techniques by analyzing internal fabric features. Experimental replicas of Middle Minoan handleless conical cups (18th cent. BC), produced using wheel-throwing-off-the-hump and wheel-coiling techniques, were investigated using X-ray micro-computed tomography (µCT). Macropores were segmented from complete 3D µCT datasets and their shape preferred orientation was quantitatively assessed through ellipsoid fitting, orientation distribution functions, and pole figure analysis. The results reveal systematic and reproducible differences between the two forming techniques: wheel-coiled vessels show predominantly horizontal pore elongation, expressed as equatorial girdle textures and vertically clustered short axes, whereas wheel-thrown vessels display inclined pore orientations, forming displaced girdles and ring-like short-axis distributions. These contrasting orientation patterns reflect distinct deformation fields imposed during vessel shaping. The study demonstrates that quantitative 3D analysis of pore orientation in whole vessels provides reliable criteria for identifying ceramic forming techniques and confirms previous qualitative observations. This approach offers a robust framework for technological analysis of ceramics and can be applied to both complete vessels and suitably oriented fragments. Full article

Magnetically driven microrobots operating in intestinal environments face two major challenges: difficulty in traversing low-height confined spaces and limited local visibility caused by mucosal obstruction. To address these issues, this study proposes a gradient-field-based force-driven control method for a mudskipper-inspired magnetic microrobot. By establishing the mapping among coil current, magnetic field, and magnetic force at the robot working point, and by solving the control input through singular value decomposition and linear programming, effective magnetic-force output along a desired direction was achieved. On this basis, two representative force-driven motions were designed. The first was a translational mode based on pulsed magnetic-force actuation for stable navigation in low-height confined spaces. The second was a lifting mode based on continuous loading and gradual adjustment of the magnetic-force upper bound to locally lift a flexible “mucosa-like” membrane, thereby simulating intestinal mucosal elevation and local visual field expansion. Experimental results showed that the robot could stably pass through narrow tunnels and effectively lift an overlying flexible membrane under vertical magnetic-force actuation. The proposed method extends both the locomotion capability and the local interaction capability of the mudskipper-inspired magnetic microrobot, and demonstrates a feasible proof-of-concept approach for confined-space navigation and localized manipulation in intestinal applications. Full article

This paper proposes a Hybrid-Field DD (HFDD) coupler designed for wireless power transfer (WPT) in mobile robots within smart manufacturing environments, utilizing a dual-coupling mechanism of magnetic and electric fields. The proposed coupler integrates Double-D coils for vertical magnetic field concentration with a split metal plate structure for enhanced electric field coupling in a compact, low-profile design. To evaluate the electromagnetic performance and the impact of inevitable eddy current interference, two distinct configurations—Front Plate Arrangement (FPA) and Back Plate Arrangement (BPA)—are analyzed through both theoretical modeling and 3D full-wave simulations (HFSSs). The comparative results demonstrate that the FPA model reduces the peak induced current intensity by 56.23 A/m compared to the BPA and achieves a peak leakage magnetic field intensity of 1.12 A/m, which is 28% lower than the 1.56 A/m observed in the BPA, offering a superior solution for suppressing leakage magnetic field and contributing to robust coupling stability. The high consistency between the proposed analytical methodology and numerical simulations underscores the theoretical robustness of the HFDD structure, establishing a clear design framework for efficient power transfer in robotic applications. Full article

This Finite Element Analysis study evaluated the biomechanical responses associated with posterior tooth intrusion using clear aligners in conjunction with buccal and palatal mini-screw anchorage. Three-dimensional finite element models were reconstructed from cone beam computed tomography images obtained from patients without craniofacial anomalies. To assess the differential effects of buccal versus palatal attachment placement in combination with a mini-screw-supported closing coil spring, two configurations of the maxillary arch were created: Model A (right side) and Model B (left side). Biomechanical parameters—including stress distribution, patterns of tooth displacement, and anchorage stability—were systematically assessed using finite element analysis. Analysis of Model A revealed buccal crown inclination and moderate extrusion of the first premolar, whereas the first molar showed limited mesial displacement along with mild buccal tipping and extrusion. In contrast, Model B revealed palatal crown inclination of the first premolar, accompanied by buccal root torque and minor intrusion; the first molar demonstrated enhanced vertical control with palatal root torque. The incorporation of palatal mini-screw anchorage in Model A contributed to diminished stress levels and reduced tooth displacement, suggesting a tendency toward more favorable force distribution and anchorage stability under the simulated conditions. Conversely, Model B experienced increased mechanical loading and more pronounced displacement. Full article

Rotatory electric motors provide low efficiency in the case of linear motion. The reason for this is the mechanical conversion system required to convert rotary torque to linear thrust force. In this paper, two novel linear machines i.e., a Dual-Mover Segmented Secondary Hybrid Excited Linear Flux Switching Machine (DMSSHELFSM) and Dual-Stator Segmented Secondary Hybrid Excited Linear Flux Switching Machine (DSSSHELFSM), were investigated and compared for a ropeless vertical elevator system. The novelties of these designs include both series and parallel magnetic circuits, a complementary AC coil structure, and their unequal primary tooth width. Results reveal that the DSSSHELFSM exhibits better performance with higher and more sinusoidal flux linkage, higher thrust force, and a robust mechanical structure. Secondly, the selected linear motor was optimized using a deterministic optimization approach. An average thrust force of 10kN and a thrust force ripple ratio of less than 10% were considered as performance constraints during the optimization process. Finally, full-scale no-load experimental results were obtained, and they validated the research. Full article

This study investigates the operation of an air source heat pump (ASHP) working with combined radiant floor (RF) and fan coil unit (FCU) heating systems in hot summer and cold winter (HSCW) regions. Intermittent heating demands and ASHP sensitivity to supply water temperature in these regions lead to insufficient steady-state assumptions, while experimental evidence on transient heating behavior, thermal comfort development, and operational limits remains limited. In this study, experiments were conducted to analyze six supply water temperatures (ranging from 35 °C to 45 °C) with respect to the system’s dynamic thermal response, vertical air temperature difference, floor surface temperature, power consumption, and coefficient of performance (COP). The results show that start-up heating is dominated by FCU convection, causing pronounced vertical temperature stratification, while radiant heat becomes dominant as the system approaches steady operation. A good vertical air temperature difference with respect to breathing zones and ankle-level temperature differences below 2 °C was achieved after sufficient operating time. Increasing the supply water temperature accelerated the heating response, where the time required for the average indoor temperature to reach 18 °C decreased from 5.5 h at 35 °C to 2.2 h at 45 °C. However, this improvement was accompanied by reduced energy efficiency, with the mean ASHP unit COP declining from 2.5 to 2.3. Excessively high supply temperatures further induced premature indoor overheating and the frequent start–stop cycling of the heat pump, thereby limiting thermal benefits and increasing power demand. These findings provide experimentally grounded insight into the operation and performance limits of ASHP RF–FCU heating systems. Full article

Dynamic wireless power transfer (DWPT) systems for in-motion electric vehicle (EV) charging often suffer from unstable power delivery due to spatial variations in magnetic coupling caused by vehicle misalignment. This study presents a stabilization-oriented DWPT design methodology that prioritizes minimizing spatial variations of mutual inductance rather than maximizing peak coupling under perfect alignment. A ferrite-backed double-D coil configuration is analyzed and refined using three-dimensional finite-element electromagnetic modeling integrated with circuit-level co-simulation to evaluate coupling behavior, magnetic field homogeneity, and power transfer efficiency under realistic dynamic misalignment conditions. The proposed design achieves a coupling coefficient of 0.50–0.55 under aligned conditions and exhibits smooth, predictable degradation for lateral offsets up to 40–50 mm. Quantitative analysis demonstrates a low spatial coupling gradient of approximately 0.001 mm⁻¹, indicating that abrupt coupling transitions are effectively suppressed during vehicle motion. The system attains a maximum power transfer efficiency of 84.37% at an 80 mm air gap, while maintaining stable performance under both lateral and vertical displacement. Comparative evaluation shows improved misalignment tolerance and coupling stability relative to conventional double-D configurations. The results demonstrate that electromagnetic field shaping focused on coupling smoothness is an effective and practical strategy for reliable dynamic wireless charging of electric vehicles. Full article

Micromachines, MEMS and actuators suffer from much more significant relative friction and wear issues than their equivalent macroscopic devices. Active magnetic bearings can be a good option to mitigate friction issues; however, their construction at microscale is still an open research topic. In this work, we have developed a micrometric-size active magnetic bearing with a simple configuration and one vertical degree of freedom. This active magnetic microbearing is composed of a coreless coil with 1 mm outer diameter, 0.3 mm inner diameter and 0.5 mm length that holds a 0.3 mm outer diameter, 0.5 mm length NdFeB N52 micromagnet. Stable magnetic levitation is achieved by regulating the coil current based on precise position measurements of the magnet obtained using the smallest commercially available Hall-effect microsensor. The microprobe integrates between the coil and magnet, reducing the total size of the device. A maximum axial load capacity of 1.16 mN/A has been demonstrated. This micromagnetic bearing is one of the smallest active magnetic bearings developed to date, demonstrating the viability of this kind of system at the micrometric scale. Full article

Accumulation of salts in irrigated soils can be detrimental not only to growing crops but also to groundwater quality. Soil salinity should be regularly monitored, and appropriate irrigation at the required leaching rate should be applied to prevent excessive salt accumulation in the root zone, thereby improving soil fertility and crop production. We combined two frequency domain electromagnetic induction (FD-EMI) mono-channel sensors (EM31 and EM38) and operated them at different heights and with different coil orientations to monitor the vertical distribution of soil salinity in a salt-affected irrigated area in Kairouan (central Tunisia). Multiple measurement heights and coil orientations were used to enhance depth sensitivity and thereby improve salinity predictions from this type of proximal sensor. The resulting multi-configuration FD-EMI datasets were used to derive soil salinity information via inverse modeling with a recently developed in-house laterally constrained inversion (LCI) approach. The collected apparent electrical conductivity (ECa) data were inverted to predict the spatial and temporal distribution of soil salinity. The results highlight several findings about the distribution of salinity in relation to different irrigation systems using brackish water, both in the short and long term. The expected transfer of salinity from the surface to deeper layers was systematically observed by our FD-EMI surveys. However, the intensity and spatial distribution of soil salinity varied between different crops, depending on the frequency and amount of drip or sprinkler irrigation. Furthermore, our results show that vertical salinity transfer is also influenced by the wet or dry season. The study provides insights into the effectiveness of combining two different FD-EMI sensors, EM31 and EM38, for monitoring soil salinity in agricultural areas, thereby contributing to the sustainability of irrigated agricultural production. The inversion approach provides a more detailed representation of soil salinity distribution across spatial and temporal scales at different depths, and across irrigation systems, compared to the classical method based on soil samples and laboratory analysis, which is a point-scale measurement. It provides a more extensive assessment of soil conditions at depths up to 4 m with different irrigation systems. For example, the influence of local drip irrigation was imaged, and the history of a non-irrigated plot was evaluated, confirming the potential of this method. Full article