Search Results (54)

Wireless power transfer (WPT) can eliminate moving power-supply harnesses in automotive power-seat systems, but seat travel and nearby metallic structures cause substantial variations in magnetic coupling and electromagnetic loss. This paper proposes a structure-aware, partially overlapped segmented transmitter and evaluates two predefined excitation states according to receiver position. In the single-segment state, only the reference segment CP1 is energized; in the simultaneous dual-segment state, CP1 and the adjacent segment CP2 are energized together. Three-dimensional finite element method (FEM) simulations compare candidate transmitter structures and evaluate the electromagnetic influence of the aluminum lower rail, steel upper rail, and steel seat frame. The transmitter geometry is determined by considering mutual inductance, winding loss, structural eddy-current loss, and partial-overlap characteristics. A three-coil equivalent circuit clarifies the branch-current distribution, and a two-state switched-capacitor network accommodates the different equivalent transmitter impedances. A 100 W, 110 kHz prototype separately evaluates representative states at x = 0 and 80 mm; automatic position-based state switching is not implemented. At x = 0 mm, CP1-only excitation achieves 78.79% efficiency. At x = 80 mm, CP1 + CP2 excitation produces 32.13 V and 72.15%, compared with 18.78 V and 67.84% under CP1-only excitation, thereby satisfying the 30 V minimum output requirement. Full article

This study proposes and validates a unified geometry-based capacitance model for four representative silicon detector architectures: planar, 3D trench electrode, 3D spherical electrode, and silicon drift detector (SDD). Closed-form analytical expressions explicitly relate capacitance to key geometric parameters—anode radius, depletion thickness, electrode depth, and electrode spacing—and the resulting geometric scaling laws are rigorously verified by combining physical modeling, TCAD simulation, and experimental measurement. A central finding is that for highly symmetric structures, capacitance is governed almost exclusively by the radius of the collecting anode and is essentially independent of the overall detector volume, thereby defining an ideal low-capacitance limit. For the SDD, a hemispherical capacitor approximation accurately captures this anode-dominated behavior, and measurements on prototypes together with independent literature data confirm that the total capacitance can be decomposed into an intrinsic geometric component and a parasitic contribution. This work provides a unified framework and direct cross-structure design guidelines for minimizing capacitance toward ultra-low-noise, high-performance silicon detectors. Full article

This paper presents the applications of a single passive loop for the mitigation of industrial frequency magnetic fields in the vicinity of medium and high voltage overhead power lines. Based on the fundamental theoretical aspects, the numerical results of the attenuation effect are simulated for different loop geometries installed at different heights under the conductors. By adding an external capacitor in the circuit, the influence of the passive element will be analyzed and the efficiency it brings in the magnetic field mitigation will be interpreted. The results highlight the fact that adding an external capacitor in passive loops can effectively reduce the nearby magnetic fields under the overhead power lines. Full article

The local twitch response (LTR) elicited during ultrasound-guided fascial hydrorelease (FHR) is conventionally attributed to dysfunctional motor endplates. Recent observational data from a companion study suggest that LTR events may occur preferentially within stacking fascia—a histologically defined multilayered, densified region of deep fascia—at sites not directly attributable to motor endplate excitation. We propose the Fascial Capacitor Model: stacking fascia can be conceptually modeled as a multilayer biological capacitor in which collagen sublayers may act as electrodes and the interposed densified hyaluronic-acid (HA)-rich loose layer may act as the dielectric, with the LTR hypothesized to reflect a transient electrophysiological discharge when a needle bridges its layers. This biophysical model is grounded in the established molecular and histological architecture of human deep fascia, and the analogy is intended as one of structural isomorphism, rather than complete functional equivalence with engineered capacitor devices. Each premise is independently supported by the primary literature from at least eight research lines spanning roughly seventy years. The apparent gap between estimated bulk discharge voltages and motor neuron threshold is addressed by reconsidering needle-tip geometry and stimulation modality, anchored by the ±6 V triboelectric measurements. The pathological extension of the RC time constant in densified fascia—lengthening by several orders of magnitude and estimated to reach the millisecond range—is supported by empirical evidence from fibrotic extracellular matrices in other connective tissues, while tissue-specific in vivo measurements in fascia remain a future task. The model is positioned as the immediate-phase complement to the Fascial Memory Reset Hypothesis, provides a candidate mechanistic interpretation for intra-procedural symptom relief—an as-yet unquantified clinical observation awaiting formal patient-reported outcome (PRO) measurement in a prospective trial—and yields falsifiable predictions. A direct empirical validation program using insulating-needle recording of spontaneous electrical activity (SEA) is in preparation at the corresponding author’s institution. Full article

Piezoelectric actuators enable ultra-fast switching due to their microsecond-scale response and high acceleration capability. This study experimentally investigates arc behavior in air, vacuum, and nitrogen using round and flat contacts driven by an amplified piezoelectric actuator. Unlike prior work focused mainly on actuation dynamics, this study provides a multi-medium comparison and investigates the coupled effects of drive operating time and contact geometry on arc characteristics. Arc tests were conducted using a capacitor discharge platform, with synchronized electrical measurements and high-speed imaging. In air (140 V, 350 A), arc voltage increased with rise time, reaching 800 V, 840 V, and 1080 V at 0.5 ms, 1 ms, and 2 ms, respectively, while shorter rise times reduced arc duration but promoted reignition. In vacuum (140–200 V), arc voltage stabilized at 80–90 V, with longer rise times extending arc duration; round contacts exhibited faster voltage rise and higher peaks. In nitrogen (140–200 V), higher voltages were obtained at shorter rise times, reaching 2680 V, 2600 V, and 2320 V at 0.5 ms, 1 ms, and 2 ms, respectively, with reduced arc duration. Across all media, round contacts consistently produced higher arc voltages than flat contacts. These results demonstrate that drive dynamics and contact geometry critically influence arc voltage and duration, providing practical guidelines for the design of high-speed piezoelectric-based switching devices. Full article

Triboelectric nanogenerators (TENGs) offer a promising route for self-powered microscale energy harvesting, yet their design optimisation remains empirically challenging due to the complex interplay of material surface physics, device geometry and operating mode. In this work, we present an integrated framework that combines atomic force microscopy (AFM) characterisation, COMSOL Multiphysics 6.0 finite element simulation and physics-informed conditional variational autoencoder (cVAE) to predict and optimise TENG output performance. Four polymer dielectric materials, HDPE, LDPE, TPU, and PMMA, were characterised via Kelvin Probe Force microscopy (KPFM) for work function, surface potential and surface roughness. Surface charge density was calculated from measured KPFM potential using the parallel plate capacitor model and used as a boundary condition in COMSOL Multiphysics simulations for contact-separation and lateral sliding TENG mode for dielectric film thicknesses of 50 µm and 100 µm. The simulated open circuit voltage (Voc) and short circuit charge (Qsc) across gap distances up to 150 mm formed the training dataset for a cVAE model with eight physicochemical condition features. The trained model demonstrated strong reconstruction accuracy (R² ≥ 0.94) and enables generative prediction across unseen design spaces. Results reveal that the LDPE/TPU pair at 50 µm thickness consistently achieves the highest electric outputs in both modes, and the sliding mode yields 25–30% higher voltages than the contact separation mode across all material pairs. This study provides a transferable data-efficient methodology for accelerating TENG material and geometry optimisation. Full article

This study details the design and development of an ultra-sensitive microwave sensor for non-invasive blood glucose monitoring, achieved by analyzing variations in the response of a split-ring resonator (SRR) through advanced engineering methodologies. There were three design phases in the development process. In the first phase, a standard SRR design was used. It had a resonant frequency of 2.975 GHz in S₂₁ and a sensitivity of only 0.0032 dB/(mg/dL). In the second phase, an interdigital capacitor (IDC) was added to the SRR structure. This made it work better and made it more sensitive, with a sensitivity of 0.015 dB/(mg/dL) at 4.1 GHz. The third phase was to use a fourth-order Moore fractal geometry to improve the resonance properties of the design a lot. From the obtained S₁₁, the maximum sensitivity was 0.042 dB/(mg/dL), which was a huge improvement in sensing efficiency compared to earlier designs. Several resonant frequencies were recorded between 4.84 and 7.56 GHz. The addition of the fractal structure made the electromagnetic field stronger in the resonant space and made the waves interact more with small changes in the biological medium, all without changing the sensor’s size (80 mm × 40 mm). These results show that fractal architecture is a promising way to create non-invasive, accurate, and easily integrated sensors in biological systems that can continuously measure blood glucose levels. Full article

This paper presents the design of a highly reconfigurable interdigital bandpass filter (BPF) developed through a three-stage design approach. In the first stage, the influence of four low-loss dielectric substrates on the filter response is systematically analyzed to identify the optimal configuration. The selected substrate demonstrates excellent performance, achieving an input return loss of −38 dB, an insertion loss of −0.9 dB at 4.30 GHz, and a wide passband corresponding to a bandwidth (BW) of 2.20 GHz. In the second stage, two variable capacitors were incorporated into the baseline geometry, enabling manual tuning of the center frequency ($f_0$) from 5.10 to 6.34 GHz, with $\left(S_{11}\right)$ better than −25 dB and ${(S}_{12})$ close to −0.60 dB. In the final stage, the capacitors were replaced by SMV1413 varactor diodes, transforming the design into a fully voltage-controlled tunable filter. This configuration provides continuous frequency agility from 4.70 to 5 GHz without modifying the physical structure, while achieving $\left(S_{11}\right)$ levels down to −40 dB and insertion loss as low as −0.7 dB. The proposed architecture offers a compact, low-loss, and electrically reconfigurable solution, making it a promising solution for next-generation RF front-ends, adaptive wireless systems, and cognitive radio applications. Two independent Electromagnetic solvers (EM) were employed to validate the filter’s performance: an EM based on the Finite Integration Technique and the Advanced Design System 2026 (ADS) solver using the Method of Moments (MoM). The close agreement between the results produced by both platforms confirms the accuracy and robustness of the proposed reconfigurable bandpass filter structure. Full article

High-voltage fuses are critical safety components in electric vehicle (EV) battery systems, yet their thermal behavior under charging currents remains insufficiently characterized. This study develops and validates a physics-based thermal resistor-capacitor (RC) network model of a high-voltage melting fuse, accounting for copper elements, quartz sand filling, and polyester casing. Experimental accelerated life tests and current step load profiles were performed in a climate chamber at 70 °C, with temperature measurements at the fuse terminals. The RC model was constructed using material properties and geometry-derived parameters, including three copper element sections, one quartz sand node, and one case node. A discretized state–space formulation was implemented to simulate the transient thermal behavior. The results reveal distinct dynamic and stationary characteristics, with thermal time constants varying strongly between fuse sections. Comparisons with experimental data demonstrate that the proposed model captures both rise time and steady-state behavior, with deviations attributable to contact resistances and parasitic effects. The findings highlight that charging currents in practical profiles typically remain below 50% of fuse current ratings, leaving optimization potential for higher permissible currents, faster charging, and reduced downtime while maintaining safety. The outcome of this model is highly relevant for lifetime prediction models. Full article

Linear passive electrical devices/components are usually characterized in the frequency domain by their impedance, i.e., the ratio of the voltage and current phasors. The use of the impedance concept does not raise particular concerns in low-frequency regimes; however, things become more complicated when it comes to rapid time-varying phenomena, mainly because the voltage depends not only on the position of the points between which it is defined but also on the choice of the integration path that connects them. In this article, based on first principles (Maxwell equations and Poynting vector flow considerations), we discuss the concept of impedance and define it unequivocally for a class of electrical devices/components with rotational symmetry. Two application examples are presented and discussed. One simple example concerns the per-unit-length impedance of a homogeneous cylindrical wire subject to the skin effect. The other, which is more elaborate, concerns a heterogeneous structure that consists of a dielectric disk sandwiched between two metal plates. For the lossless situation, the high-frequency impedance of this device (circular parallel plate capacitor) reaches zero when the frequency reaches a certain critical frequency f_c; then, it becomes inductive and increases enormously when the frequency reaches another critical frequency at 1.6 f_c. The influence of losses on the impedance of the device is thoroughly investigated and evaluated. Impedance corrections due to dielectric losses are analyzed using a frequency-dependent Debye permittivity model. The impedance corrections due to plate losses are analyzed by considering radial current distributions on the outer and inner surfaces of the plates, the latter exhibiting significant variations near the critical frequencies of the device. Full article

Artificial muscles underlie exciting, novel technologies that have many wide-reaching applications: exoskeleton actuation, walker robots, prosthetics and stealthy underwater propulsion. Actuating these muscles via electrostatic forces promises excellent energy efficiency and output force density and a high strength-to-weight ratio. Building these muscles through 3D-printed and conductive microfluidics promises fast mass production at a low cost. A microfluidic double-helix weave as a potential solution for the architectural design of these actuators has previously been reported. However, more recent experimental work showed that a weave architecture was not manufacturable at the necessary scale, given the limitations of current 3D-printing technology. Herein, several alternative architectures are presented. They are more advanced and more compatible with current manufacturing requirements, and offer additional benefits. The presented experimental results confirm their improvements in manufacturability. These advanced architectures represent a significant step towards the experimental proof of principle and the practical implementation of electrostatic microfluidic 3D-printed artificial muscles. Full article

Powder metallurgy (PM) offers several advantages over conventional melt metallurgy, including improved homogeneity, fine grain size, and pseudo-alloying capabilities. Transitioning from conventional methods to PM can result in significant enhancements in material properties and production efficiency by eliminating unnecessary process steps. Dynamic compaction techniques, such as impulse and explosive compaction, aim to achieve higher powder density without requiring sintering, further improving PM efficiency. Among these techniques, magnetic pulse compaction (MPC) has gained notable interest due to its unique process mechanics and distinct advantages. MPC utilizes the rapid discharge of energy stored in capacitors to generate a pulsed electromagnetic field, which accelerates a tool to compress the powder. This high-speed process is particularly well-suited for compacting complex geometries and finds extensive application in industries such as powder metallurgy, welding, die forging, and advanced material manufacturing. This paper provides an overview of recent advancements and applications of MPC technology, highlighting its capabilities and potential for broader integration into modern manufacturing processes. Full article

The present study examines the relationship between thermal and configurational entropy in two resistors in parallel and in series. The objective is to introduce entropy in electric circuit analysis by considering the impact of system geometry on energy conversion in the circuit. Thermal entropy is derived from thermodynamics, whereas configurational entropy is derived from network modelling. It is observed that the relationship between thermal entropy and configurational entropy varies depending on the configuration of the resistors. In parallel resistors, thermal entropy decreases with configurational entropy, while in series resistors, the opposite is true. The implications of the maximum power transfer theorem and constructal law are discussed. The entropy generation for resistors at different temperatures was evaluated, and it was found that the consideration of resistor configurational entropy change was necessary for consistency. Furthermore, for the sake of generalization, a similar behaviour was observed in time-dependent circuits, either for resistor–capacitor circuits or circuits involving degradation. Full article

This work consists of the analysis and design of a LC series resonant inverter with reactive element control for induction heating hardening applications. This novel method uses a current-controlled variable transformer (VT) to control the reflected inductance of the inductor in the resonant, and a magnetic energy recovery switch (MERS) to vary the influence of the capacitor as a reactive power compensation element. This converter topology allows quality factor (Q) or operating frequency $\left(f_{sw}\right)$ to be adjusted, making it possible to harden workpieces of different geometries and materials with a single converter. In the article, the design of both elements will be studied and tested. Experimental results were carried out with a 10 kW induction heating inverter prototype, with a frequency range of 60 kHz to 100 kHz and a quality factor of 6 to 10, measuring efficiencies above 95%. Full article

Related to microelectronics’ reliability, lifetime estimation methods have gained importance, especially for surface-mounted devices. The virtual testing of electronic assemblies necessitates the geometry modeling and finite element analysis of the solder joint. The effect of the simplification of the solder geometry on the predicted lifetime is an open question. Furthermore, there is still not yet straightforward guidance for the choice of the material model and fatigue lifetime model. In this study, the impact of the geometry input method, the material model and the lifetime model choice is investigated on two different surface-mounted capacitors in a simulation-based benchmark analysis under thermal cyclic loading. Four different types of solder geometry modeling approaches are compared, among which one is a physics-based approach. Ten different fatigue models founded on plastic and viscoplastic material models are benchmarked. The results show that the component standoff height and the solder volume have a positive effect on the lifetime, while the capacitor size has a slightly negative effect on the lifetime. The results also suggest that approximate geometries can be used to replace the physics-based model with a restriction for the minimum standoff height. Full article