Search Results (6,296)

Background: The radius, a crucial bone in the human forearm, supports and facilitates complex movements like pronation and supination. Its anatomical landmarks, including Lister’s tubercle, provide vital attachment points for muscles, tendons, and ligaments involved in upper limb mobility. This study provides a detailed osteometric analysis of the dorsal radial tubercle of the radius, aiming to improve our understanding of its anatomy and clinical significance. Material and Methods: The study was conducted in the Department of Anatomy and Embryology, using 56 radius bones from cadavers. After applying inclusion and exclusion criteria, 46 bones remained in the study group. Results: The study found a significant positive correlation between the length of the radius and the width of the distal epiphysis. The distance from the suprastyloid crest to the dorsal radial tubercle (SC-DT) and the distal epiphysis width were strongly associated with the development of the distal radial epiphysis. The distance between the dorsal radial tubercle and the oblique ridge (OR-RI) and between the oblique ridge and the radial incisure (DT-OR) also showed a strong positive correlation with the distal epiphysis width. Conclusions: In conclusion, the osteometric study performed reveals significant correlations between the bony elements of distal radius epiphysis that can provide valuable information regarding anatomic variability and surgical treatment of distal radial epiphyseal fractures. Full article

This study aims to explore the influence of random pore characteristics inside rock mass on the fracture mechanical properties of rock under tensile stress. By means of numerical simulation based on the improved smoothed particle hydrodynamics (SPH) method, a specific kernel function approximate integral interpolation form and discrete particle superposition expression form are constructed to handle physical processes. The maximum tensile stress criterion and fracture marker ω are introduced to improve the traditional smooth kernel function for dealing with crack propagation. Meanwhile, the center and radius information of circular pores are generated using random numbers to create a rock model with random pores. The research results show that in terms of crack propagation morphology, as the pore percentage increases, the crack gradually changes from a straight propagation slightly disturbed by pores to an overall fragmentation propagation with frequent branching and coalescence; when the pore size increases, the crack propagation changes from a complex network-like shape frequently disturbed by small pores to a relatively simple through fracture controlled by key nodes of large pores. In terms of the stress–strain law, the increase in pore percentage leads to a decrease in the elastic modulus and peak strength of the rock and a weakened post-peak ductility; when the pore size increases, the elastic modulus first decreases and then increases, the peak strength changes similarly, and the post-peak characteristics change from complex fluctuations to a stable transition. The conclusion indicates that the pore percentage and size have a significant and complex influence on the mechanical properties of the rock. Full article

In view of the high-level, thick, and hard roof in a mine in Shaanxi, it is difficult for existing technology to solve the problem of frequent rock bursts, which are caused by the direct weakening of the whole underground layer. In this paper, a technology for preventing rock bursts using the long-distance drilling and blasting of a thick and hard roof in a high drilling field is proposed. The authors used theoretical analyses, numerical simulations, and other research methods to analyze the mechanisms of pressure relief and load reduction achieved by this technology, determined its layout parameters and layers, and carried out engineering practices in 2412 working faces in a mine in Shaanxi. The results show that the long-distance drilling and blasting technology can achieve the aim of unloading the pressure drop load by arranging a high-level drilling field to achieve the whole-layer presplitting of the thick and hard roof above the working face. According to the orthogonal test method, when using long-distance drilling and blasting under the condition of a high-level roof, the choice of the blasting layer is the biggest factor affecting the change in overburden subsidence. Using the identification basis of the main control disaster causing the layer of overburden, it was determined that 52~67 m above the coal seam of the 2412 working faces was the blasting layer. According to the periodic weighting interval of the working face and the development radius of the fractures in the blasting surrounding rock, the blast hole spacing was determined to be 30 m. After long-distance drilling and blasting, the frequency and energy of micro seismic events were reduced, the entry deformation was reduced compared with the common roof deep-hole blasting technology, and the pressure relief effect of the long-distance drilling and blasting technology was better. These research conclusions can provide theoretical support for the prevention and control of rock bursts during mining production under similar conditions by reducing the load and the unloading pressure on thick and hard roof layers that are difficult to unload from the source. Full article

Gaze tracking and estimation are essential for understanding human behavior and enhancing human–computer interactions. This study introduces an innovative, cost-effective solution for real-time gaze tracking using a standard webcam, providing a practical alternative to conventional methods that rely on expensive infrared (IR) cameras. Traditional approaches, such as Pupil Center Corneal Reflection (PCCR), require IR cameras to capture corneal reflections and iris glints, demanding high-resolution images and controlled environments. In contrast, the proposed method utilizes a convolutional neural network (CNN) trained on webcam-captured images to achieve precise gaze estimation. The developed deep learning model achieves a mean squared error (MSE) of 0.0112 and an accuracy of 90.98% through a novel trajectory-based accuracy evaluation system. This system involves an animation of a ball moving across the screen, with the user’s gaze following the ball’s motion. Accuracy is determined by calculating the proportion of gaze points falling within a predefined threshold based on the ball’s radius, ensuring a comprehensive evaluation of the system’s performance across all screen regions. Data collection is both simplified and effective, capturing images of the user’s right eye while they focus on the screen. Additionally, the system includes advanced gaze analysis tools, such as heat maps, gaze fixation tracking, and blink rate monitoring, which are all integrated into an intuitive user interface. The robustness of this approach is further enhanced by incorporating Google’s Mediapipe model for facial landmark detection, improving accuracy and reliability. The evaluation results demonstrate that the proposed method delivers high-accuracy gaze prediction without the need for expensive equipment, making it a practical and accessible solution for diverse applications in human–computer interactions and behavioral research. Full article

Thresholds can be an effective tool in conservation planning, as they can form a defensible target for habitat conservation or restoration. Generalized thresholds must be used with caution, however, as threshold responses may vary with species and spatial scale. The objectives of this study were to identify the scales at which forest-dwelling birds respond to both habitat availability and critical thresholds in forest cover associated with their occurrence, and to assess if life history traits relate to either scale of response or critical threshold. Using point count data from the Ontario Breeding Bird Atlas, I generated concentric buffers ranging from 100 m to 10 km radius around a random subset of point counts and described forest cover and species occurrence within each buffer. I assessed the likelihood of occurrence of each species at each scale of analysis using logistic regression and identified forest cover thresholds below which the occurrence of each species becomes unlikely using fitted regression curves and ROC plots. Species varied in their response to both landscape scale and forest cover, based on relative growth rate, clutch size, and site fidelity. The mean response to forest cover was 30.8%, with landscape scale ranging from 200 m to 9 km. Despite this range, pragmatic approaches to conservation planning are still possible. Full article

Focusing on the three critical factors influencing laser communication systems operating in marine environments: atmospheric turbulence disturbances, atmospheric attenuation, and optical aberration effects, in this paper, we employ numerical simulation methods to systematically investigate the influence of four typical Zernike aberrations (defocus, y-coma, spherical aberration, and y-secondary quadrupole) on laser atmospheric transmission characteristics and system bit error rates. A comparison of their atmospheric transmission performance with that of the aberration-free state is also presented. The results show that reducing turbulence strength or increasing receiver aperture radius can effectively mitigate the scintillation effect of intensity fluctuations. Among the four typical aberrations, the fluctuation range of the relative change rate of the scintillation index for y-coma aberration relative to the aberration-free state is the largest. In weak turbulence and short-distance laser transmission over the sea, the beam drift caused by these four aberrations is not significant, and stronger turbulence strength or higher weight coefficients lead to more severe beam expansion. The on-axis logarithmic intensity probability density distribution of laser beams with different aberrations approximately follows a log-normal distribution. The skewness (S) and kurtosis (K) of the logarithmic intensity distribution are negatively correlated and always satisfy S < 0 and K > 0. Additionally, we found that as turbulence strength increases, turbulence effects significantly raise the required signal-to-noise ratio (SNR) values to achieve a bit error rate of 10⁻⁹. When turbulence strength reaches a certain level, the impact weights of different aberrations on system performance may undergo changes. These results can provide theoretical references for the design and optimization of laser system parameters in marine laser communication. Full article

Optical fiber-based acoustic detectors for ultrasound imaging in medical field feature plano-concave Fabry–Perot cavities integrated on fiber tips, realized via dip-coating. This technique imposes constraints on sensor geometry, potentially limiting performance. Lab-on-Fiber technology enables complex three-dimensional structures with precise control over geometric parameters, such as the curvature radius. A careful investigation of the optical and mechanical aspects involved in the sensors’ performances is crucial for determining the design rules of such probes. In this study, we numerically analyzed the impact of curvature on the optical and acoustic properties of a plano-concave cavity using the Finite Element Method. Performance metrics, including sensitivity, bandwidth, and directivity, were compared to planar Fabry–Perot configurations. The results suggest that introducing curvature significantly enhances sensitivity by improving light confinement, especially for cavity thicknesses exceeding half the Rayleigh zone (∼45 μm), reaching an enhancement of 2.5 a L = 60 μm compared to planar designs. The curved structure maintains high spectral quality (FOM) despite 2% fabrication perturbations. A mechanical analysis confirms no disadvantages in acoustic response and bandwidth (∼40 MHz). These findings establish curved plano-concave structures as robust and reliable for high-sensitivity polymeric lab-on-fiber ultrasound detectors, offering improved performance and fabrication tolerance for MHz-scale bandwidth applications. Full article

Permanent Magnet Linear Oscillating Motors (PMLOMs) are popular in micro-positioning systems, biomedical devices, and refrigeration compressors due to their simple structure, high efficiency, rapid response, and quiet operation. This paper proposes a method for the analysis and optimization of electromechanical systems that employs a moving magnet linear oscillating motor. A simplified magnetic circuit method model was built to derive an electromagnetic thrust formula, and the initial design parameters of the motor and the thrust at the equilibrium position were calculated. Subsequently, a finite element model was developed, and a multi-objective optimization method was applied to refine the key dimensions of the motor to enhance its thrust characteristics. Furthermore, an analysis of the resonant characteristics of the electromechanical coupled system was conducted to identify the optimal operating frequency for the optimization scheme. Finally, the experimental validation of the optimized design was performed on a prototype, with the measured data showing a general correlation with the trends observed in the simulation analysis results. The effectiveness of this system analysis method was validated through experimental data. The results demonstrate that the thrust at the initial position is linearly correlated with both the outer arc radius of the permanent magnet and its mechanical pole arc coefficient. Additionally, the axial length of the outer stator, the axial spacing between the two outer stators, and the axial length of the magnets serve as key influencing parameters for the thrust characteristics within the effective stroke range. Furthermore, when the motor operates at its mechanical resonance frequency, it can attain the maximum efficiency. Full article

When testing soft biological samples using the Atomic Force Microscopy (AFM) nanoindentation method, data processing is typically based on equations derived from Hertzian mechanics. To account for the finite thickness of the samples, precise extensions of Hertzian equations have been developed for both conical and parabolic indenters. However, these equations are often avoided due to the complexity of the fitting process. In this paper, the determination of Young’s modulus is significantly simplified when testing soft, thin samples on rigid substrates. Using the weighted mean value theorem for integrals, an ‘average value’ of the correction function (symbolized as g(c)) due to the substrate effect for a specific indentation depth is derived. These values (g(c)) are presented for both conical and parabolic indentations in the domain 0 < r/H ≤ 1, where r is the contact radius between the indenter and the sample, and H is the sample’s thickness. The major advantage of this approach is that it can be applied using only the area under the force–indentation curve (which represents the work performed by the indenter) and the correction factor g(c). Examples from indentation experiments on fibroblasts, along with simulated data processed using the method presented in this paper, are also included. Full article

To optimize the robotic MIG welding process for joining 316 L stainless steel sheets and to clearly understand the process, a new numerical model for a combined heat source, based on a Gaussian surface and Gaussian cylinder, was developed using ANSYS software. After confirming the proper welding parameter combination for producing a weld bead with a good appearance, the model could be developed using the parameter combination. The influence of four parameters—effective heat delivery radius, the depth and heat distribution coefficients of the Gaussian surface, and the Gaussian cylinder heat source effects on the bead width and penetration—was explored using the model, and then a general and convenient method was proposed to effectively and reasonably set the parameters of the combined heat source. Finally, the numerical calculation results for the shape of the fusion line of the weld bead section could be obtained under different input powers and different welding speeds. The numerical calculation results had small errors compared to the experiments results. Hence, this model could realize temperature field simulation and weld bead formation prediction. This work can be used to accurately and effectively predict the robotic MIG welding process in the academic research and supply references for actual production. Full article

Urban community open spaces are external spaces for public use that meet the needs of residents in their daily lives, and which gradually become the basic unit for activities and fitness. The arrival of the era of ‘national fitness’ requires the formation of public activity spaces that benefit all ages. Yet most construction targets of urban community open spaces are homogenised and are not diversified for all age groups. This phenomenon leads to a spatial and temporal mismatch between the allocation of space for community sports activities and the needs of residents. We quantitatively analysed time periods, demanded area and preferred types of activities required by all age groups. We further defined the objectives for the provision of physical activity functions in community open spaces. We also constructed a method for matching and optimising the supply and demand of sports and fitness functions in community open spaces, which was based on the calculation of supply and demand, the matching analysis model and the optimisation of supply and demand gaps. Accordingly, based on the distribution of demand points, we can clarify the amount and radius of each point, and calculate the matching relationship with the Maximum Capacity Limitation Coverage Model. When the implementation rate of demand at the covered points is less than 67%, it means that there is a demand gap. In response to the gap, optimisation has been achieved by establishing a time-sharing utilisation mechanism and using excessive supply space for renovation. The results of the study can help optimise the mismatch and long-term layout of physical activities for all residents in urban communities. The proposed sustainable optimising strategy suggests the importance and necessity of meeting the spatial needs of sports activities for all age groups in high-density cities with insufficient open spaces. Full article

The geometry of non-pressurized tunnel intersections governs the hydraulic behavior of the confluence flows, which are critical to the safe operation of pumped storage power stations. To address the issue of water surface levels exceeding the permissible height of the vertical walls at the intersection of the sediment discharge and emptying tunnels close to the lower reservoir of a pumped storage power station, a hydraulic model with a scale of 1:45 was constructed to optimize the intersection design. The optimization process included replacing the straight connection with an arc connection, incorporating an energy dissipation basin into the emptying tunnel, reducing the intersection angle, and increasing the arc radius. During the optimization, the hydraulic behavior of the confluence flow was thoroughly analyzed. This study determined that an arc connection with a 21° intersection angle represented the optimal design. Using the RNG k-ε turbulence model and the volume-of-fluid (VOF) method, a three-dimensional (3D) numerical model was developed to further evaluate the flow patterns, velocity fields, and bottom pressure distributions under both the optimized-design and model-verification conditions. The numerical simulation results, validated against experimental data, exhibited close agreement. The findings demonstrate that the optimized design ensures compliance with specifications, as the maximum water depth no longer exceeds the height of the straight walls. This study offers valuable insights for optimizing tunnel intersections of high-elevation-difference non-pressurized tunnels in pumped storage power stations. Full article

Equations are developed for the relative sliding velocities, entrainment velocities, forces, friction coefficients, effective radius of curvature, oil film thickness, friction loss, and meshing efficiency for a novel closed movable tooth gear reducer. Using these equations, the relative sliding velocities and entrainment velocities of the reducer are studied. The meshing efficiencies and their changes along with meshing positions and main parameters are analyzed. Changes of the meshing efficiencies along with load torque are also studied. An efficiency experiment of the reducer prototype is carried out. Results indicate that the meshing efficiency of the novel closed reducer increases with increasing eccentric distance. When an error in the eccentric distance occurs, the meshing efficiency is significantly reduced. The measured efficiency is close to the calculated one, supporting the theoretical studies. Full article

The application of membrane filtration, particularly micro- and ultra-filtration, in food and pharmaceutical industries often faces the issue of protein fouling. In this study, we aimed to fabricate a free-standing ternary tungsten trioxide/carbon nanotube/zinc oxide (WO₃/CNT/ZnO)–chitosan composite photocatalytic membrane via wet processing and infiltration techniques to address the fouling issue. Infiltration with low molecular weight chitosan was found to enhance the mechanical stability of the ternary composite photocatalytic membrane. The ternary composite photocatalytic membrane with a 0.16 g ternary photocatalyst load demonstrated 86% efficiency in the degradation of bovine serum albumin (BSA) under sunlight irradiation for 120 min. A reduction in permeation flux accompanied by an increase in BSA rejection was observed as the loading of the ternary photocatalyst in the ternary composite photocatalytic membrane was increased. This can be associated with the decreased average porosity and mean pore radius. The ternary composite photocatalytic membrane demonstrated reasonably good antifouling behavior with an R_fr of 82% and an R_if of 18%. The antifouling property demonstrated by the ternary composite photocatalytic membrane is important in maintaining the reusability of the membrane. Full article

Tidal energy, as a sustainable and environmentally friendly energy source, has attracted widespread attention in recent years. The technology of blade active pitch control is the key technology to cope with tidal velocity change and improve the stability and efficiency of horizontal-axis tidal generator sets. When solving the problem of speed variation, the core algorithm is the key to ensuring stable operation and improving the efficiency of power generation. When traditional PID is used to manage complex systems, the controller faces the challenge of complex parameter tuning and insufficient robustness. The application of a particle swarm optimization (PSO)–PID controller and fuzzy PID controller in the independent interval system of tidal generator sets is introduced for the first time in this paper. This paper presents a comparative study of unified pitch control and independent pitch control (using electric pitch control) for a three-rotor tidal generator with a rated capacity of 300 kw and a blade radius of 8.5 m. Simulation was carried out on the MATLAB/Simulink (2023a) platform to evaluate the performance of the two controllers under different flow rates and interference conditions. The results show that the PSO-PID controller has significant advantages in reducing overshoot, speeding up response times, and improving power generation efficiency. At the same time, the PSO-PID controller also shows superior performance in pitch angle adjustment frequency and generator output power and realizes timely and effective system stability control. Full article