Simulation Analysis on Quasistatic Characteristics of Multistage Face Gears with Double Crown Surface

The multistage face gears are the core component of the planetary gear train, which is symmetrically meshed by multiple single-stage face gear and multiple cylindrical gears. However, it is difficult to synchronize the contact between face gears and cylindrical gear due to the tooth number differences. Thus, the interference problems between two stages and big stress concentration are obvious. The crown surface configuration technology and structure design were introduced to optimize the meshing condition. To improve the double crown design feasibility and meshing stability, it is necessary to establish a reasonable multistage face gears pair simulation model to evaluate various influence factors on the contact condition and quasi-static characteristics of multistage face gears structure. The relevant scatter plots are fitted by comparing the contact results with different crown quantities and friction coefficients to intuitively obtain the variation regularity of maximum deformation, maximum strain, maximum stress and maximum strain energy. The natural frequency and mode coefficient are also determined by modal analysis under these two conditions. All the above mentioned studies verified the contact conjugate properties of double crown surface configuration were suitable. The results can provide a foundation for structure optimization and transmission reliability of multistage face gears

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Electromagnetic–Structural Coupling Analysis and Optimization of Bridge-Connected Modulators in Coaxial Magnetic Gears

This study presents a comprehensive analysis and optimization methodology for bridge-connected modulators in coaxial magnetic gears. A novel harmonic modeling method incorporating magnetic saturation through permeability convolution matrices and multiple-layer radial subdivision is developed, achieving computational efficiency 20 times greater than finite element analysis with comparable accuracy (deviation < 3.2%). The research establishes an electromagnetic–structural coupling framework that captures the complex interactions between the magnetic field distribution and mechanical deformation, revealing critical trade-offs between electromagnetic performance and structural integrity. Multi-objective optimization using an improved NSGA-II algorithm identifies Pareto-optimal solutions balancing torque density, structural safety, efficiency, and thermal stability. Experimental testing validates that bridge width ratios between 0.05 and 0.07 provide optimal performance, delivering torque densities exceeding 80 kNm/m3 while maintaining stress ratios below 0.65 of material yield strength. Thermal analysis demonstrates that optimized configurations maintain operating temperatures below 70 °C with reduced thermal gradients. Vibration characteristics exhibit a strong correlation with bridge width, with wider bridges providing enhanced stability at higher speeds. The findings establish practical design guidelines for high-performance magnetic gears with improved reliability and manufacturability, advancing the fundamental understanding of electromagnetic–structural interactions in field-modulated magnetic gear systems

A Comprehensive Analysis of the Loss Mechanism and Thermal Behavior of a High-Speed Magnetic Field-Modulated Motor for a Flywheel Energy Storage System

This paper presents a comprehensive analytical framework for investigating loss mechanisms and thermal behavior in high-speed magnetic field-modulated motors for flywheel energy storage systems. Through systematic classification of electromagnetic, mechanical, and additional losses, we reveal that modulator components constitute approximately 45% of total system losses at rated speed. Finite element analysis demonstrates significant spatial non-uniformity in loss distribution, with peak loss densities of 5.5 × 105 W/m3 occurring in the modulator region, while end-region losses exceed central-region values by 42% due to three-dimensional field effects. Our optimized design, implementing composite rotor structures, dual-material permanent magnets, and integrated thermal management solutions, achieves a 43.2% reduction in total electromagnetic losses, with permanent magnet eddy current losses decreasing by 68.7%. The maximum temperature hotspots decrease from 143 °C to 98 °C under identical operating conditions, with temperature gradients reduced by 58%. Peak efficiency increases from 92.3% to 95.8%, with the η > 90% region expanding by 42% in the speed–torque plane. Experimental validation confirms model accuracy with mean absolute percentage errors below 4.2%. The optimized design demonstrates 24.8% faster response times during charging transients while maintaining 41.7% smaller speed oscillations during sudden load changes. These quantitative improvements address critical limitations in existing systems, providing a viable pathway toward high-reliability, grid-scale energy storage solutions with extended operational lifetimes and improved round-trip efficiency

Study on kinematic characteristics of planetary multistage face gears transmission

A planetary gear transmission system with multistage face gears combinations as core component can easily realize the variable speed in differential transmission ratios with structural advantages. In order to improve the transmission stability and loading capacity, it is necessary to set up a reasonable kinematic model for multistage face gears pair. This study focuses on the kinematic characteristics of multistage face gears structure with double crown surface by the methods of numerical calculation and experimental verification. The transmission error and efficiency solving models are established by numerical calculation method to analyze the influences of each factor in detail. Then the correctness of the above numerical models are verified with transmission error and efficiency experiment. In addition, the numerical results are compared with the experimental results to further indicate the important influences of the multistage face gears components on the transmission error and efficiency of whole transmission system. The results can provide references for the dynamic and experimental study of multistage face gears in some degree. </jats:p

Electrochemical performance and stability of electrolyte-supported solid oxide fuel cells based on Y-substituted SrTiO3 ceramic anodes

Electrolyte-supported solid oxide fuel cells (SOFCs) based on 6% Sc2O3-stabilized ZrO2 (6ScSz) electrolyte and Y0.07Sr0.895TiO3 (YST) anode materials were prepared. Ni and CGO particles were infiltrated on the pore walls within the ceramic anode framework as catalysts for the anode reaction. The performance, redox stability, and time-dependent degradation of the cells were tested. Electrochemical impedance spectroscopy was used to determine the non-Ohmic losses of the cells. Possible reasons for the observed performance degradation were investigated. The mechanism of the anode reaction is also discussed based on the electrochemical results

Microstructural variations and their influence on the performance of solid oxide fuel cells based on yttrium-substituted strontium titanate ceramic anodes

Donor-substituted strontium titanates have been widely recognised as alternative anode materials to the state-of-the-art Ni/YSZ cermets in solid oxide fuel cells (SOFCs). Electrolyte-supported SOFCs based on Y0.07Sr0.895TiO3 ceramic anodes with different microstructural designs were prepared. Ni or Ni with Ce0.8Gd0.2O1.9 (CGO) was infiltrated onto the pore walls within the ceramic anode framework as an electrocatalyst for anode reactions. Performances and electrochemical impedance spectroscopy measurements of the cells were analysed in detail to observe the influence of low ionic conductivity of Y0.07Sr0.895TiO3 to cell performance, to understand how to control the degradation of the cells, and to obtain a possible mechanism for the anode processes. The anode design containing both functional and current collecting layers with sufficient Ni-CGO infiltration is favourable for high power output and low performance degradation