Search Results (324)

In this paper, the accuracy of basic and advanced spiral inductor models for gallium nitride (GaN) integrated inductors is evaluated. Specifically, the experimental measurements of geometrically scaled circular spiral inductors, fabricated in a radio frequency (RF) GaN-on silicon technology, are exploited to estimate the errors of two lumped geometrically scalable models, i.e., a simple π-model with seven components and an advanced model with thirteen components. The comparison is performed by using either the standard performance parameters, such as inductance (L), quality factor (Q-factor), and self-resonance frequency (SRF), or the two-port scattering parameters (S-parameters). The comparison reveals that despite a higher complexity, the developed advanced model achieves a significant reduction in SRF percentage errors in a wide range of geometrical parameters, while enabling an accurate estimation of two-port S-parameters. Indeed, the correct evaluation of both SRF and two-port S-parameters is crucial to exploit the model in an actual circuit design environment by properly setting the inductor geometrical parameters to optimize RF performance. Full article

To address the issues of large errors, low accuracy, and time-consuming simulations in finite element (FE) models of tapping processes, which hinder the identification of optimal structural parameters, this study integrates FE simulation with experimental testing to optimize the structural parameters of spiral taps specifically designed for stainless steel. Initially, single-factor experiments were conducted to analyze the influence of mesh parameters on experimental outcomes, leading to the identification of optimal mesh coefficients. Subsequently, the accuracy of the FE tapping simulation model was validated by comparing trends in axial force, torque, and chip morphology between simulations and actual tapping experiments. Orthogonal experimental design combined with entropy weight analysis and range analysis was then employed to conduct FE simulations. The results indicated that the optimal structural parameter combination is a helix angle of 43°, cone angle of 19°, and cutting edge relief amount of 0.18 mm. Finally, based on this combination, optimized spiral taps were manufactured and subjected to comparative performance testing. The results demonstrated significant improvements: the average maximum axial force decreased by 33.22%, average maximum torque decreased by 13.41%, average axial force decreased by 38.22%, and average torque decreased by 24.87%. Error analysis comparing corrected simulation results with actual tapping tests revealed axial force and torque error rates of 5.04% and 0.24%, respectively. Full article

Stones in farmland soil affect the efficiency of agricultural mechanization and the efficient growth of crops. In order to solve the problems of traditional stone pickers, such as large soil disturbance, high soil content and low picking rate, this paper introduces the Archimedean curve with constant radial expansion characteristics into the design of the core working parts of the drum picker and designs a new type of drum stone picker. The key components such as spiral blades, rollers, and scrapers were theoretically analyzed, the structural parameters of the main components were determined, and the reliability of the spiral blades was checked using ANSYS Workbench software. Through the preliminary stone-picking performance test, the forward speed of the stone picker, the rotation speed of the drum, and the starting sliding angle of the spiral blade were determined as the test influencing factors. The picking rate and soil content of the stone picker were determined as the test indicators. The response surface test was carried out in the Design-Expert13.0 software. The results show that, when the forward speed of the stone picker is 0.726 m/s, the drum speed is 30 rpm, and the initial sliding angle of the spiral blade is 26.214°, the picking rate is 91.458% and the soil content is 3.513%. Field tests were carried out with the same parameters, and the picking rate was 91.42% and the soil content was 3.567%, with errors of 0.038% and 0.054% compared with the predicted values, indicating that the stone picker meets the field operation requirements. These research results can provide new ideas and technical paths for improving the performance of pickers and are of great value in promoting the development of advanced harvesting equipment and the efficient use of agricultural resources. Full article

This study presents a robust numerical framework for evaluating the upper-bound ultimate bearing capacity of shallow foundations in cohesive and C-phi soils using a self-developed finite element method. The model incorporates multi-segment zero-thickness interface elements to accurately simulate soil discontinuities and progressive failure mechanisms, based on the Mohr–Coulomb failure criterion. In contrast to optimization-based methods such as discontinuity layout optimization (DLO) or traditional finite element limit analysis (FELA), the proposed approach uses predefined failure mechanisms to improve computational transparency and efficiency. A variety of geometric failure mechanisms are analyzed, including configurations with triangular, circular, and logarithmic spiral slip surfaces. Particular focus is given to the transition zone, which is discretized into multiple blocks to enhance accuracy and convergence. The method is developed for two-dimensional problems under the assumption of elastic deformable-plastic behavior and homogeneous isotropic soil, with limitations in automatically detecting failure mechanisms. The proposed approach is validated against classical theoretical solutions, demonstrating excellent agreement. For friction angles ranging from 0° to 40°, the computed bearing capacity factors N_c and N_q show minimal deviation from the analytical results, with errors as low as 0.04–0.19% and 0.12–2.43%, respectively. The findings confirm the method’s effectiveness in capturing complex failure behavior, providing a practical and accurate tool for geotechnical stability assessment and foundation design. Full article

Endometrial stromal cells (EnSCs) undergo decidualization in response to progesterone. Decidualization facilitates spiral artery remodeling, immune tolerance in the endometrium, and fetal cell invasion and placentation—all essential for successful embryo implantation. Therefore, we aimed to investigate whether ergothioneine (EGT) plays a role in reproduction, particularly in decidualization and implantation. In this study, we found that solute carrier family 22 member 4 (SLC22A4), a specific transporter of EGT—a functional food ingredient with strong anti-aging properties—is upregulated in decidualized EnSCs. The effects of EGT were examined using uterine tissues from patients, primary cultured EnSCs, EnSC cell lines, and co-cultures with a fetal cell line. We observed a significant increase in SLC22A4 expression in secretory-phase human uterine tissue, decidualized EnSCs, and EnSC cell lines. We also found that EGT regulates insulin-like growth factor binding protein 1 expression, which promotes placentation. In co-cultures of EnSC and fetal cell lines, EGT upregulated ectonucleoside triphosphate diphosphohydrolase 1 and major histocompatibility complex, class I, G expression in fetal cell lines—both critical for placentation. These findings suggest that EGT is crucial to regulating decidualization and its markers, particularly insulin-like growth factor-binding protein 1, which contributes to placentation. Full article

Aiming at the existing fertilizer distributor’s lack of stability of fertilizer discharge and uniformity of fertilizer discharge, which affects the precise application of fertilizer, a design and testing of a multi-row spiral quantitative fertilizer distributor was designed. The design principle and working principle of the fertilizer distributor are described, and the parameter ranges of centrifugal cone discs’ cone angle, cone disc inclination, cone disc rotation speed, etc., are determined. The Elementary Discrete Element Method (Referred to as EDEM in the following) simulation analysis software was adopted to carry out the simulation analysis of the fertilizer discharge process of the fertilizer discharger, to study the influence of each parameter on the fertilizer discharge performance and the optimal combination parameters of the fertilizer discharger. Taking the coefficient of variation for the consistency of fertilizer application amount among rows and the coefficient of variation for the consistency of fertilizer application amount within the same row as the evaluation indicators, and taking the cone angle of the centrifugal cone disk, the cone disk inclination angle, and the cone disk rotational speed as the test factors, multi-factor and multi-level experiments were carried out. The simulation test results show that the optimal parameter combination of the fertilizer discharger is the rotational speed of the centrifugal cone disk at 95 r/min, the cone angle of the cone disk at 16.7°, and the blade inclination angle of the cone disk at 2.7°. Using potassium sulphate compound fertilizer as the test material, the bench test on the fertilizer discharge performance and adaptability of the fertilizer distributor when the speed of centrifugal cone discs was 30~110 r/min was carried out to verify the fertilizer discharge performance of the fertilizer distributor. The results of the validation test showed that the coefficient of variation for the consistency of fertilizer application amount among rows of fertilizer distributor at different rotational speeds was lower than 4.25%, the coefficient of variation for the consistency of fertilizer application amount within the same row was lower than 3.21%, which meets the requirement of fertilizer discharge quality. The research provides technical support for enhancing the performance of fertilizer distributors and achieving precise fertilizer application, thereby playing an active role in improving fertilization efficiency and promoting sustainable agricultural development. Full article

Against the backdrop of the booming digital economy, innovation has emerged as the core driving force for enterprise development, with employees’ innovative capabilities serving as a key competitive advantage for innovative enterprises. Adopting grounded theory as the methodological framework, we obtain multi-source data to investigate the factors influencing employees’ innovative capabilities and their underlying mechanisms. Furthermore, we develop a theoretical model elucidating the formation mechanism of employees’ innovative capabilities in human–machine collaboration contexts, identifying four core dimensions—innovation drivers, human–AI collaboration patterns, knowledge conversion pathways, and technological breakthroughs—that dominantly shape these capabilities. Thus, we reveal that the formation of innovative capabilities constitutes a dynamic interplay of technology empowerment, cognitive restructuring, and collaborative reinforcement and demonstrate its spiral progression characterized by “triggering, collaboration, and iteration”. This research not only contributes to academic discourse but also offers actionable theoretical and practical insights for innovative enterprises to enhance employees’ innovative capabilities, thereby fostering sustainable development in global competition. Full article

The soil slopes in nature are normally unsaturated, heterogeneous, and even carry cracks. In order to assess the stability of slope with crack under steady unsaturated flow and non-uniform conditions, this work proposes a novel discretization-based method to generate the rotational failure mechanism in the context of the kinematic limit analysis. A point-to-point strategy is used to generate the potential failure surface of the failure mechanism. The failure surface consists of a series of log-spiral segments instead of linear segments employed in previous studies. Two kinds of cracks—open cracks and formation cracks—are considered in the stability analysis. The maximum depth of the vertical crack is modified by considering the effect of the unsaturated properties of soils. According to the work–energy balance equation, the explicit expression about the slope factor safety for different crack types is obtained, which is formulated as a multivariate nonlinear optimization problem optimized by an intelligent optimization algorithm. Numerical results for different unsaturated parameters and non-uniform distribution of soil strength are calculated and presented in the form of graphs for potential use in practical engineering. Then, a sensitivity analysis is conducted to find more insights into the effect of unsaturation and heterogeneity on the crack slopes. Full article

In this study, we hypothesized and tested that physical parameters (flow, transport, and water depth) have a significantly greater influence on phosphorus (P) retention in wetlands than biogeochemical factors. Specifically, we evaluated the null hypothesis (H₀), that no significant difference exists between the influence of physical and biogeochemical parameters on phosphorus retention, against the alternative hypothesis (H₁), that physical parameters are more influential. We investigated two large wetlands (stormwater treatment areas, STAs) in south Florida: STA34C2A, which is dominated by emergent aquatic vegetation (EAV), and STA2C3, which is dominated by submerged aquatic vegetation (SAV). Building on Part 1, which mapped spatial flow resistance (K) as a vegetation-type-independent proxy for hydraulic resistance, this study (Part 2) applied a novel high-frequency (hourly) data approach with time-lagged regression modeling to estimate total phosphorus (TP) outflow concentrations. The key variables included inflow TP concentration, vegetation volume, water depth, nominal hydraulic residence time (HRT), hydraulic loading rate (HLR), phosphorus loading rate (PLR), and time lag (“P-spiral”). Multi-linear regression models for each STA identified inflow TP and water depth, a controllable physical parameter, as the most significant predictors of TP outflow, while the hour of day (a temporal proxy) contributed the least. Optimal model performance occurred with lag times of 8 and 9 days, producing R² values of 0.5788 (STA34C2A) and 0.5354 (STA2C3). In STA34C2A, high TP retention was linked to shallow water depth, dense EAV, and low K values, indicating high hydraulic resistance and reduced short circuiting. In contrast, lower TP retention in STA2C3 was associated with longer flow paths, sparse SAV, and high K values, suggesting less hydraulic control despite similar nominal HRTs. These results provide empirical support for rejecting the null hypothesis (H₀) in favor of the alternative (H₁): physical parameters, especially water depth, hydraulic resistance, and inflow dynamics, consistently exert a stronger influence on P removal than biogeochemical factors such as PLR. The findings highlight the importance of optimizing flow and depth controls in wetland design and management to enhance phosphorus removal efficiency in large, constructed wetland systems. Full article

This study addresses the optimization of control performance for automatic voltage regulator systems by proposing a fractional-order PIDD² (FOPIDD²) controller design method based on the hybrid Black-winged Kite Algorithm (BWOA). To overcome the challenges of complex parameter tuning and adaptability to high-dimensional nonlinear optimization in PID controllers, the BWOA integrates the precise search mechanism of the Black-winged Kite Algorithm (BKA) with the spiral encircling strategy of the Whale Optimization Algorithm (WOA). By dividing high-fitness individuals into subgroups for parallel optimization, combined with an elitism preservation mechanism and Levy flight perturbation, the BWOA effectively balances global exploration and local exploitation capabilities, preventing premature convergence. Furthermore, a multi-factor objective function is adopted to optimize the six parameters of the FOPIDD² controller. Numerical simulations in MATLAB evaluate the controller’s performance across multiple dimensions, including transient response, frequency-domain stability, trajectory tracking, parameter uncertainty, and disturbance rejection, with comparisons to other recent controllers. Simulation results demonstrate that the BWOA-FOPIDD² controller achieves superior performance in most metrics. Therefore, the proposed method provides an efficient hybrid optimization framework for AVR system controller design. Full article

Symmetrical bearing raceway led to the axial sliding of rolling elements, which is a crucial factor in shortening the operational lifespan. This study addresses this limitation through three-step advancements: first, a parametric equation for logarithmic spiral raceways is developed by analyzing their asymmetric geometric features; second, based on the geometrical model, we systematically investigate the parameters of the logarithmic spiral that affects the bearing performance metrics; and finally, a novel fatigue life prediction framework that integrates static mechanical analysis with raceway parameters establishes the theoretical foundation for optimizing the raceway parameters. The results of the model analysis show that the error of the maximum contact stress verified by the finite element method is less than 8.3%, which verifies the model’s accuracy. Increasing the contact angle α of the outer ring from 82 to 85 can increase fatigue life by 15.6 times while increasing the initial polar radius O of the inner ring from 7.8 mm to 8.1 mm will cause fatigue life to drop by 86.9%. The orthogonal experiment shows that the contact angle α of the outer ring has the most significant influence on the service life, and the optimal parameter combination (clearance δ of 0.02 mm, inner race and outer race strike angles α of 85°, an inner race initial polar radius $r_o$ of 7.8 mm, and an outer race initial polar radius $r_o$ of 7.9 mm) achieves a 60.7% fatigue life increase. The findings provide theoretical support and parameter guidance for the optimal bearing design with logarithmic spiral raceways. Full article

In this paper, we present a novel passive dual-tuned magnetic metasurface, which can enhance the field distribution produced by a closely placed radio-frequency coil for both ¹H and ²³Na 1.5 T MRI imaging. In particular, the proposed solution comprises a 5 × 5 capacitively loaded array, in which each unit-cell is composed of two concentric spiral coils. Specifically, the unit-cell internal spiral coil operates at the proton Larmor frequency (64 MHz), whereas the external is at the sodium one (17 MHz). Therefore, the paper aims to demonstrate the possibility of enhancing the magnetic field distribution in transmission and reception for 1.5 T MRI scanners by using the same metasurface configuration for imaging both nuclei, thus drastically simplifying the required instrumentation. We first describe the theoretical model used to design and synthetize the dual-tuned magnetic metasurface. Next, full-wave simulations are carried out to validate the approach. Finally, we report the experimental results acquired by testing the fabricated prototype at the workbench, observing a good agreement with the theoretical design and the numerical simulations. In particular, the metasurface increases the transmission efficiency T_x in presence of a biological phantom by a factor 3.5 at 17 MHz and by a factor 5 at 64 MHz, respectively. The proposed solution can pave the way for MRI multi-nuclei diagnostic technique with better images quality, simultaneously reducing the scanning time, the invasiveness on the patient and the overall costs. Full article

In the past two decades, there has been a tremendous increase in demand for services requiring a high bandwidth, a low latency, and high data rates, such as broadband internet services, video streaming, cloud computing, IoT devices, and mobile data services (5G and beyond). Optical wireless communication (OWC) technology, which is also envisioned for next-generation satellite networks using laser links, offers a promising solution to meet these demands. Establishing a line-of-sight (LOS) link and initiating communication in laser links is a challenging task. This process is managed by the acquisition, pointing, and tracking (APT) system, which must deal with the narrow beam divergence and the presence of satellite platform vibrations. These factors increase acquisition time and decrease acquisition probability. This study presents a framework for evaluating the acquisition time of four different scanning methods: spiral, raster, square spiral, and hexagonal, using a probabilistic approach. A satellite platform vibration model is used, and an algorithm for estimating its power spectral density is applied. Maximum likelihood estimation is employed to estimate key parameters from satellite vibrations to optimize scan parameters, such as the overlap factor and beam divergence. The simulation results show that selecting the scan path, overlap factor, and beam divergence based on an accurate estimation of satellite vibrations can prevent multiple scans of the uncertainty region, improve target satellite detection, and increase acquisition probability, given that the satellite vibration amplitudes are within the constraints imposed by the scan parameters. This study contributes to improving the acquisition process, which can, in turn, enhance the pointing and tracking phases of the APT system in laser links. Full article

In a competitive industrial setting, optimizing machining processes is important for enhancing surface quality and productivity. This study focuses on optimizing pocket milling parameters for 5083 H111 aluminum alloy using three toolpath strategies: Zig-Zag, Parallel Spiral, and One-Way. To achieve these goals, the Taguchi method, Grey Relational Analysis (GRA), ANOVA, and visual amplification were employed to evaluate the influence of cutting speed (V_c), feed per tooth (f_z), and axial depth of cut (a_p) on surface roughness and production rate. For the Zig-Zag and Parallel Spiral tool paths, cutting speed was the most important factor affecting surface roughness. For the One-Way strategy, axial penetration was the most important factor. The Parallel Spiral toolpath, under the V_c of 150 m/min, the f_z of 0.025 mm/tooth, and the a_p of 1.0 mm (A3-B3-C1) configuration, achieved the best balance between surface finish and production rate. Visual analysis also showed significative differences in how rough the wall was along perpendicular and parallel tool paths, which made it clear that finishing passes are needed in some cases. This research shows that using both statistical methods and visual amplification together makes process optimization more organized and effective, which leads to better machining performance. Full article

: Image segmentation is an important part of ore particle size detection, and the quality of image segmentation directly affects the accuracy and reliability of particle size detection. Due to the poor quality and low efficiency of ore particle image segmentation in ore size detection, developing a fast and accurate algorithm for segmenting ore particle images remains a global challenge. However, the quality of image segmentation is closely related to calculating ore density, improving beneficiation efficiency, and evaluating crushing effectiveness. In this paper, a novel image segmentation algorithm is proposed, combining the K-means algorithm with a hybridized IGK-means. Firstly, the IGWO_SOA, by introducing a nonlinear convergence factor and incorporating the migration and spiral search mechanisms of SOA, is applied to overcome the weakness of being sensitive to initial centroids of the traditional K-means. IGWO_SOA is utilized to iteratively search for the optimal values of the initial cluster centers, which are then output as the results for subsequent clustering segmentation. An industrial experiment was conducted for multiple comparisons, which proved that the IGK-means has the characteristics of better image segmentation quality and being insensitive to illumination. The PSNR of the images segmented by IGK-means can reach up to 24.24 dB, and the FSIM can reach up to 0.2733, which proves the superiority and practicality of the algorithm in this paper. Full article