Search Results (792)

Photovoltaic/Thermal (PV/T) systems are a technology designed to simultaneously convert solar energy into both electrical and thermal energy. The overall conversion efficiency of these systems can be significantly enhanced by effectively cooling the photovoltaic (PV) module. To this end, this paper presents a comparative experimental study of a PV panel under three distinct configurations: operating with a no cold plate, with an ordinary cold plate, and with a spiral coil cold plate. The system’s photo-thermoelectric efficiency was evaluated by measuring key parameters, including the PV panel’s surface temperature, electrical power output, and the water tank temperature. The results indicate that the spiral coil configuration demonstrated a marked superiority in temperature regulation over the baseline case, achieving a maximum temperature reduction of 13.8 °C and an average reduction of 10.74 °C. Furthermore, a stable temperature drop exceeding 10 °C was maintained for 74.07% of the experimental duration. When compared to the ordinary cold plate, the spiral coil configuration continued to exhibit superior performance, delivering maximum and average temperature drops of 3.6 °C and 2.16 °C, respectively, while sustaining a cooling advantage of over 2 °C for 66.67% of the test period. These findings conclusively demonstrate that the spiral coil cold plate is the most effective configuration for enhancing the system’s overall performance. Full article

This study investigates fiber content and orientation in prefabricated slab elements made of ultra-high-performance fiber-reinforced concrete (UHPFRC), using novel non-destructive measurement using a coil’s quality factor, where the coil is put to one side of the specimen only. This allows the analysis of slab specimens of arbitrary size. That then allows an accurate quality control of elements made in the prefabrication industry. This study presents an experimental campaign designed to evaluate the non-destructive principle’s accuracy and practical feasibility. Twenty-five large slab specimens were made in an industrial prefabrication plant using various casting methods to introduce different flow-induced fiber parameters. The slabs were subjected to this non-destructive testing, then destructive bending tests and CT scanning to tie the results together and validate the non-destructive results. The results showed that the coil’s quality factor values correspond well to the distribution (concentration) and orientation of fibers, and the method reliably reveals potential defects of the material and can predict the element’s mechanical properties. Full article

The hydrodynamic and reaction characteristics of poly-alpha-olefin (PAO) polymerization in a continuous stirred tank reactor (CSTR) under Eulerian–Eulerian multiphase flow and a finite-rate chemical kinetics model were studied in this paper. A mathematical framework correlating 1-decene conversion with operational and structural parameters was established. Numerical simulations revealed an axial circulation flow pattern driven by combined impellers, with internal coils enhancing heat exchange and flow guidance. The gaseous catalyst, injected below the turbine impeller, achieved rapid dispersion and low gas holdup. The results demonstrated that 1-decene conversion exhibited insensitivity to impeller speed under fully turbulent mixing (mixing time <0.15% of space time), suggesting limited mass transfer benefits from further speed increases. Conversion positively correlated with temperature and space time, albeit with diminishing returns at prolonged durations. Series reactor configurations improved conversion efficiency, though incremental gains decreased with additional units. Optimal reactor design should balance conversion targets with economic factors, including energy consumption and capital investment. These findings provide critical insights into scaling PAO polymerization processes, emphasizing the interplay between reactor geometry, mixing dynamics, and reaction kinetics for industrial applications. Full article

Due to its high-temperature resistance, high thermal conductivity, electrical conductivity, excellent chemical stability, and outstanding mechanical and electrochemical properties, graphite has been widely applied in various fields. However, the current production process of high-purity graphite is faced with issues such as high energy consumption and insufficient reduction degree. This study utilized COMSOL Multiphysics 6.0 to couple the electromagnetic field, temperature field, velocity field, and flow field during the purification process of graphite. The dimensionless analysis method is adopted to investigate the influence of parameters such as current intensity, magnetic field frequency and concentration on the reduction degree of graphite feedstock, and the energy consumption in the furnace. Through numerical simulation, the interaction mechanism among various parameters under different parameter combinations is compared and analyzed, and the temperature change and fluid motion state of graphite feedstock during the electromagnetic induction heating process are predicted. When the current is 500 A, the average temperature inside the furnace gradually rises with the increase in the magnetic field frequency. This is because the energy input from induction coil and the energy output due to radiative heat loss gradually reach a dynamic equilibrium state. Furthermore, the average temperature inside the furnace continuously increases with the enhancement of the current, and for every increase of 50 A, the average temperature rises by approximately 200 K. Additionally, through dimensionless analysis, the optimal operating conditions for this induction furnace were determined to be a current intensity of 600 A and a magnetic field frequency of 14 kHz. Under these conditions, the reduction degree of the material reaches 99.69%, which achieves efficient purification and economical energy consumption. This study provides a theoretical basis for the optimization of operating parameters in graphite purification process, which is of great significance for improving production efficiency, reducing energy consumption, and promoting the application of high-purity graphite. Full article

In this work a multi-criteria analysis and an optimization tool were developed, which allows the substitution of fossil-based solvents with bio-based alternatives based on Hansen solubility parameters and various physical parameters, such as the boiling point, evaporation rate, viscosity or wetting behavior. The proof of concept was achieved by formulating two different paints used in coil coatings using the bio-based solvents, and they performed equally as well as their fossil-based counterparts. A potential decrease in CO₂ emissions was determined by a life cycle assessment and cradle-to-grave analysis of bio- and fossil-based solvents, which showed a large sustainability bonus when using solvents based on biomass. The introduced methodology provides initial insights into substituting currently used solvents systematically. Overall, implementing bio-based solvents is a viable drop-in method to decrease the environmental impact of paints and coatings, while maintaining the same performance. Full article

Aluminum alloys under long-term service or repetitive stress are prone to small fatigue cracks (FCs) with arbitrary orientations, necessitating eddy current probes with focused magnetic fields and directional selectivity for reliable detection. This study presents a flexible printed circuit board (FPCB) probe with a double-layer planar excitation coil and a double-layer differential receiving coil. The excitation coil employs a reverse-wound design to enhance magnetic field directionality and focusing, while the differential receiving coil improves sensitivity and suppresses common-mode noise. The probe is optimized by adjusting the excitation coil overlap and the excitation–receiving coil angles to maximize eddy current concentration and detection signals. Finite element simulations and experiments confirm the system’s effectiveness in detecting surface cracks of varying sizes and orientations. To further characterize these defects, two time-domain features are extracted: the peak-to-peak value ($\Delta$P), reflecting amplitude variations associated with defect size and orientation, and the signal width ($\Delta$W), primarily correlated with defect angle. However, substantial overlap in their value ranges for defects with different parameters means that these features alone cannot identify which specific parameter has changed, making prior defect classification using a Transformer-based approach necessary for accurate quantitative analysis. The proposed method demonstrates reliable performance and clear interpretability for defect evaluation in aluminum components. Full article

The paper presents some design principles of an inductive displacement transducer for measuring the displacement of rock specimens under high hydrostatic pressure. It consists of a single-layer, coreless solenoid mounted directly onto the specimen and connected to an LC oscillator located outside the pressure chamber, in which it serves as the inductive component. The specimen’s deformation changes the coil’s length and inductance, thereby altering the oscillator’s resonant frequency. Paired with a reference coil, the system achieves strain resolution of ~100 nm at pressures exceeding 400 MPa. Sensor design challenges include both electrical parameters (inductance and resistance of the sensor, capacitance of the resonant circuit) and mechanical parameters (number and diameter of coil turns, their positional stability, wire diameter). The basic requirement is to achieve stable oscillations (i.e., a high Q-factor of the resonant circuit) while maintaining maximum sensor sensitivity. Miniaturization of the sensor and minimizing the tensile force at its mounting points on the specimen are also essential. Improvement of certain sensor parameters often leads to the degradation of others; therefore, the design requires a compromise depending on the specific measurement conditions. This article presents the mathematical interdependencies among key sensor parameters, facilitating optimized sensor design. Full article

Gellan gum (Gellan), a versatile polysaccharide applied in gel formation and prebiotic formulations, is often processed to tailor its molecular properties. Previous studies employed gamma irradiation and chemical hydrolysis, though without addressing systematic scaling behavior. This study investigates the structural and conformational modifications of Gellan in dilute aqueous salt solutions using a safer and eco-friendly approach: atmospheric low-dose electron beam (e-beam) degradation coupled with viscosity analysis. Native and E-beam-treated Gellan samples (0.05 g/cm³ in 0.1 M KCl) were examined by relative viscosity at varying temperatures, with intrinsic viscosity and molar mass determined via Solomon–Ciuta and Mark–Houwink relations. Molar mass degradation followed first-order kinetics, yielding rate constants and degradation lifetimes. Structural parameters, including radius of gyration and second virial coefficient, produced scaling coefficients of 0.62 and 0.15, consistent with perturbed coil conformations in a good solvent. The shape factor confirmed preservation of an ideal random coil structure despite irradiation. Conformational flexibility was further analyzed using theoretical models. Transition state theory (TST) revealed that e-beam radiation lowered molar mass and activation energy but raised activation entropy, implying reduced flexibility alongside enhanced solvent interactions. The freely rotating chain (FRC) model estimated end-to-end distance (R_θ) and characteristic ratio (C_∞), while the worm-like chain (WLC) model quantified persistence length (l_p). Results indicated decreased R_θ, increased l_p, and largely unchanged C_∞, suggesting diminished chain flexibility without significant deviation from ideal coil behavior. Overall, this work provides new insights into Gellan’s scaling laws and flexibility under aerobic low-dose E-beam irradiation, with relevance for bioactive polysaccharide applications. Full article

The reliability of the generator circuit breaker (GCB) switching coil affects the safe and stable operation of the power system, in which the faults of abnormal voltage, poor contact, and mechanical jamming of the switching coil can easily lead to the refusal of the circuit breaker, which threatens the safety of the power grid. In order to study the fault characteristics of the GCB switching coil, this paper combines multi-physical field simulation and experimental testing, establishes the electromagnetic field simulation model of the switching coil, and analyzes the characteristics of current waveforms under typical faults such as voltage abnormality, poor contact, and core jamming. Through simulation and testing to verify the mechanism of current waveform distortion under different fault states, demonstrated the change rule of characteristic parameters when the fault occurs, and provided a basis for the diagnosis of the operation status of the switching coil based on current waveform. Full article

Electromagnetic separators are widely used in new energy battery purification, resource recycling, and mineral processing. However, coil heating can cause a decline in separation performance and damage to coil insulation. To ensure the stable operation of electromagnetic separators, cooling plates are employed to effectively mitigate temperature rise. To explore a high-performance and economical cooling method, this paper employs CFD finite element analysis for the structural optimization of cooling plates. First, the paper investigates the flow heat characteristics of S-shaped cooling plates. Numerical simulations are performed to analyze the variation of fluid characteristics with different numbers of water channels. Regression equations linking structural parameters to performance indicators are derived, and the optimal channel number and hydraulic diameter are determined. Furthermore, to enhance heat transfer efficiency, an innovative semicircular groove structure is introduced on the cooling plate walls. An optimization strategy based on a genetic algorithm is developed to determine the optimal groove parameters. A simulation shows that the optimized cooling plate reduces coil temperature by 12.63 °C with a decrease of 15.31% compared with the original design. Finally, a prototype with optimized parameters is manufactured after the experimental results of the two test points and the simulation results reveal errors of 0.26% and 0.96%, respectively. The experimental results align well with the simulations, confirming the reliability of the experimental results and the feasibility of the optimization strategy, and providing a reference for future cooling plate designs. Full article

Eye tracking, a fundamental process in gaze analysis, involves measuring the point of gaze or eye motion. It is crucial in numerous applications, including human–computer interaction (HCI), education, health care, and virtual reality. This study delves into eye-tracking concepts, terminology, performance parameters, applications, and techniques, focusing on modern and efficient approaches such as video-oculography (VOG)-based systems, deep learning models for gaze estimation, wearable and cost-effective devices, and integration with virtual/augmented reality and assistive technologies. These contemporary methods, prevalent for over two decades, significantly contribute to developing cutting-edge eye-tracking applications. The findings underscore the significance of diverse eye-tracking techniques in advancing eye-tracking applications. They leverage machine learning to glean insights from existing data, enhance decision-making, and minimize the need for manual calibration during tracking. Furthermore, the study explores and recommends strategies to address limitations/challenges inherent in specific eye-tracking methods and applications. Finally, the study outlines future directions for leveraging eye tracking across various developed applications, highlighting its potential to continue evolving and enriching user experiences. Full article

The wireless charging of electric vehicles (EVs) has drawn much attention as it can ease the charging process under different charging situations and environmental conditions. However, power transfer rate and efficiency are the critical parameters for the wide adaptation of wireless charging systems. Different investigations are presented in the literature that have aimed to improve power transfer efficiency and to maintain constant power at the load side. This paper introduces a Maximum Efficiency Point Tracking (MEPT) system designed specifically for a reconfigurable S-LCC compensated wireless charging system. The reconfigurable nature of the S-LCC system supports the constant current (CC) and constant voltage (CV) mode of operation by operating S-LCC and S-SP mode. The proposed system enhances power transfer efficiency under load fluctuations, coil misalignments, and a wide range of operating conditions. The developed S-LCC compensated system inherently maintains the power transfer rate constantly under a majority of load variations. Meanwhile, the inclusion of the MEPT method with the S-LCC system provides stable and maximum output under different coupling and load variations. The proposed MEPT approach uses a feedback mechanism to track and maintain the maximum efficiency point by iteratively adjusting the DC-DC converter duty ratio and by monitoring load power. The proposed approach was designed and tested in a 3.3 kW laboratory scale prototype module at an operating frequency of 85 kHz. The simulation and hardware results show that the developed system provides stable maximum power under a wider range of load and coupling variations. Full article

By-pass switches play a crucial role in high-power electrical equipment, where reliable mechanical insertion and stable electrical contact are essential for safety and performance. However, few computational models have been developed to characterize the coupled mechanical–electrical behavior of by-pass switches with axially canted coil springs, which limits the understanding of their structural parameter effects. Motivated by this gap, this work investigates the mechanical insertion force and electrical contact resistance of by-pass switches with axially canted coil spring by combining analytical modeling and finite element simulation. The variations in mechanical insertion force, contact force and associated contact resistance as functions of the insertion displacement are presented. The total electrical contact resistance could comprise three components of resistance, that is, constriction resistance between multiple turns of coil spring wires and pin, constriction resistance between multiple turns of coil spring wires and V-shape groove, and the bulk resistance. The effects of structure feature parameters (including turns, spring wire diameter, inclination angle of axially canted coil spring wire, cylindrical pin chamfer radius and V-shape groove angle) are evaluated. Subsequently, the associated empirical formulas are established to guide the design of by-pass switches with axially canted coil springs. Full article

This work presents a novel wireless charging system for unmanned aerial vehicles (UAVs), which employs conical-shaped coils that also function as landing gear. By integrating electromagnetic simulation, circuit modeling, and system-level evaluation, we introduce an innovative coil design that enhances wireless power transfer (WPT) efficiency while reducing misalignment sensitivity. The conical geometry naturally facilitates mechanical alignment upon drone landing, thereby improving inductive coupling. High-frequency simulations were carried out to optimize the coil parameters and evaluate the link efficiency at 6.78 MHz, an ISM-designated frequency. Our experimental testing confirmed that the proposed conical coil achieves high power transfer efficiency (up to 94%) under practical conditions, validating the effectiveness of the geometry. The characteristics of the designed coil make it highly suitable for use with Class EF amplifiers operating in the same frequency range; however, detailed amplifier hardware implementation and efficiency characterization were beyond the scope of this study and are reserved for future work. The results demonstrate the potential of the proposed system for deployment in UAV field applications such as surveillance, delivery, and remote sensing. Full article

This paper presents a novel diagnostic method that employs the fuel injection system as a sensor for monitoring internal combustion engine pressure, analysing series resistance to detect connector degradation, and evaluating needle movement within the injector’s magnetic core. Experimental results showed that reducing the injector needle opening from 100% to 20% of its maximum displacement caused up to a 35% reduction in peak current amplitude and a 0.2 ms delay in coil charging. Increasing fuel pressure from 0.3 bar to 2.5 bar resulted in a rise in peak current by approximately 35% and an extension of coil charging delay by 0.4 ms. Furthermore, increasing the series resistance from 0.2 Ω to 2.0 Ω reduced the current amplitude by nearly 50% and significantly distorted the waveform, simulating connector oxidation or wear. Comparative analysis of reference and fault current waveforms confirmed that variations in electrical parameters correlate with injector needle displacement, fuel pressure, and resistance changes. Finally, an automated diagnostic system was developed that achieved over 90% accuracy in independently detecting injector faults based on current waveform characteristics. Full article