Search Results (226)

The distribution of gas–water two-phase flow in near-horizontal wells is influenced by factors such as wellbore inclination and phase flow rates. To explore these effects, a laboratory loop simulating downhole conditions was used to conduct experiments under varying inclinations and flow parameters. Flow patterns were classified based on visual observations and existing theory, and scatter plots were used to analyze flow regime boundaries. Three classification models were developed and compared. The proposed PNN–XGBoost framework integrates explicit second-order feature crossing with XGBoost-based importance selection prior to probabilistic neural network classification. Among the evaluated models, the PNN–XGBoost approach achieved the highest predictive performance. The model was further validated using 3D wellbore holdup imaging, confirming its robustness in flow pattern identification and its applicability to practical well logging interpretation. Full article

Accurate prediction of thermo-mechanical behavior in Fused Deposition Modeling (FDM) is often limited by mismatches between idealized Computer-Aided Design (CAD) geometry and path-dependent material deposition. This paper presents a G-code-driven, filament-level modeling and process-simulation workflow for complex geometries and infill strategies, especially toolpaths with in-plane inclinations. Extrusion segments are parsed from slicing G-code to obtain endpoints and process parameters, and each filament is reconstructed as a path-aligned rectangular bead using a dedicated local coordinate system. Progressive deposition is simulated in ANSYS Parametric Design Language (APDL) via an element birth–death method, enhanced by a centroid-based element selection strategy that reduces dependence on strictly aligned hexahedral partitions and improves robustness for complex meshes. A nonlinear transient thermal analysis is performed, and temperatures are mapped to the structural model through an indirect thermo-mechanical coupling scheme to predict warpage and residual stresses. Case studies on square plates with triangular and hexagonal infills (with/without sidewalls and a bottom base) show that the high-temperature zone follows newly deposited paths with peak temperatures near 220 °C, while displacement and von Mises stress accumulate and are strongly affected by infill topology and boundary conditions. Full article

Background and Objectives: Accurate prediction of lip prominence changes following orthodontic treatment remains challenging because traditional profile analyses rely on isolated reference lines that do not account for combined nasal and chin morphology. The aesthetic triangle framework integrates these structures and may provide a more comprehensive evaluation of lip position. Materials and Methods: This correlative clinical study evaluated 82 orthodontic patients undergoing bimaxillary incisor repositioning. Lateral cephalograms and standardized profile photographs were obtained before and after treatment. Lip position was assessed relative to the aesthetic triangle boundaries, and dentoalveolar changes were quantified using standard incisor measurements. Lip thickness was also analyzed as a potential modulating factor. Results: Mandibular incisor inclination demonstrated a moderate positive correlation with anterior displacement of the lower lip within the aesthetic triangle (Pearson r = 0.45, p < 0.01). Multiple linear regression analysis confirmed IMPA as a significant predictor of lower lip migration (β = 0.41), explaining approximately 21% of the observed variance (R² = 0.21). In contrast, maxillary incisor inclination (U1–SN) showed weaker and statistically inconsistent associations with upper lip position. Compartment analysis revealed that approximately 32% of patients exhibited anterior migration of the lower lip from the posterior to the central aesthetic triangle compartment following treatment. These findings suggest that mandibular incisor inclination exerts a measurable influence on lower lip prominence, whereas upper lip positional changes appear to be less directly related to maxillary incisor variables. Conclusions: The aesthetic triangle provides a clinically meaningful framework for interpreting orthodontic soft-tissue changes as spatial migration rather than isolated linear measurements. Lower lip prominence responds predictably to dentoalveolar mechanics, whereas upper lip position also depends on soft tissue morphology. Full article

The present numerical study simultaneously investigates the aerodynamic performance, shape optimization, and aeroacoustic characteristics of modified leading-edge wavy wings for the NACA 0020 airfoil. Unlike conventional passive flow-control approaches, the present study proposes a collaborative vortex–slot control strategy, where streamwise vortices induced by a wavy leading edge interact constructively with momentum injection from upper-surface slot channels. Flow field is analyzed at a Reynolds number of 290,000 and various angles of attack (AoA) utilizing Computational Fluid Dynamics (CFD). Three leading-edge wavy wing configurations, namely A3L11, A3L40 and A11L40, are examined and further modified by introducing streamwise slots near the leading edge on the upper surface of the wing. Three slot diameters (0.07c, 0.10c, and 0.13c) are examined at a constant draft angle of 7.5°, which represents the inclination of the slot relative to the wing surface. The numerical results are validated against experimental data available in the literature. The findings indicate that the A3L11 configuration with a 0.07c slot diameter, as well as the A11L40 configuration at high angles of attack, outperform the baseline wavy wing. This improvement is attributed to the slotting mechanism, which enhances surface suction and streamwise momentum, thereby improving boundary-layer behavior. An increase in aerodynamic efficiency, quantified by the lift-to-drag ratio, is observed at 20° AoA for all configurations. To further enhance performance, shape optimization is performed by optimizing the slot diameter and the distance between the chord line and the slot center using a Genetic Algorithm (GA), with the A11L40 configuration at 20° AoA identified as the optimal design. The optimized configuration yields an overall aerodynamic performance improvement of approximately 27.76% compared to the smooth wing, while broadband aeroacoustic source modeling indicates a relative reduction in predicted noise-source intensity relative to the baseline modified wing. The results are presented through combined quantitative metrics and qualitative flow analyses, demonstrating the potential applicability of the proposed optimization framework to low-Reynolds-number aerodynamic and aeroacoustic design problems, such as those encountered in small-scale air vehicles, bio-inspired wings, and noise-sensitive systems. Full article

This study explores how immersive e-learning technologies influence entrepreneurial intention among business education students, with a focus on the mediating role of learning satisfaction. Using a quantitative approach, data were collected from 561 final-year undergraduate students enrolled in business and entrepreneurship programs at globally ranked universities. The relationships between immersive learning design features, learning satisfaction, and entrepreneurial intention were analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM). The study draws on Experiential Learning Theory, Self-Determination Theory, and Expectancy–Value Theory to explain how immersive learning experiences shape entrepreneurial motivation. The results show that interactivity, experiential engagement, and personalization positively influence entrepreneurial intention, primarily by enhancing learning satisfaction. Students are more inclined toward entrepreneurial careers when immersive learning environments support autonomy, meaningful engagement, and perceived value. In contrast, high levels of realism and multisensory intensity do not consistently strengthen entrepreneurial intention, suggesting that excessive immersion may create cognitive strain or diminishing motivational returns under certain conditions. These findings highlight the importance of balanced and learner-centered immersive learning design rather than increased technological intensity alone. From a practical perspective, the study suggests that business schools should integrate immersive technologies in ways that emphasize experiential learning, adaptability, and cognitive balance. However, the findings should be interpreted with caution due to the cross-sectional design, reliance on self-reported data, and focus on final-year students. Overall, the study provides a nuanced understanding of how immersive e-learning can support entrepreneurial intention while also identifying important boundary conditions that shape its effectiveness. Full article

Thin liquid film flows of nanofluids over porous surfaces are central to applications ranging from microfluidic thermal management to precision coating technologies. This study investigates the hydrodynamic and thermal stability of a nanofluid flowing down a non-uniformly heated inclined porous plane subject to the Beavers-Joseph slip boundary condition. Using the long-wave approximation, a nonlinear evolution equation governing the film thickness is derived. The stability characteristics are systematically analyzed via linear stability theory, weakly nonlinear analysis, and fast Fourier transform (FFT) numerical simulations. Quantitative results indicate that the porous medium permeability, density difference, and Marangoni number act as destabilizing factors; specifically, increasing the porous parameter $\beta$ (from 0 to 0.3), the density ratio ${\zeta }_0$ (from 0 to 5), and the Marangoni number $Mn$ (from 0 to 0.3) significantly reduces the critical Reynolds number and accelerates the onset of interfacial instabilities. In contrast, increasing the nanoparticle volume fraction $\varphi$ from 0 to 0.3 exerts a dominant stabilizing effect by elevating the critical Reynolds number and shrinking the unstable wavenumber domain. Furthermore, nonlinear simulations confirm that higher nanoparticle concentrations effectively suppress the saturation amplitude of disturbances, promoting the eventual stabilization of the liquid film. Full article

The effect of helmet shape on aerodynamic drag is numerically investigated when cyclists lean during cornering in individual cycling races. Five helmet models (H1–H5) with varying curvatures are constructed, and under the conditions of a vehicle speed of 20 m/s and a 45° body inclination, the SST k-ω turbulence model and grid independence verification (final grid count: 6.75 million) are used to systematically analyze the distribution of velocity, vortex, pressure, and wall shear stress fields. The results show that increasing helmet curvature enlarges the windward area, intensifies rear vortex strength, slows pressure recovery, and ultimately increases drag. The H3 helmet is identified as the optimal choice for individual races due to its stable flow field and minimum drag (268.4 N). Further analysis of different initial speeds (5–25 m/s) reveals that as speed increases, the boundary layer velocity gradient rises, with wall shear stress (0–5 Pa) and drag (100–500 N) also increasing accordingly, while the pressure field decreases gradually due to the Bernoulli effect. Full article

Background: The pressure reduction range in traditional protective coal mining is often set conservatively, resulting in diminished actual pressure reduction effects near the mining boundary. Therefore, analyzing the stress and permeability evolution patterns at the mining boundary is particularly essential. Method: A three-dimensional numerical model was established according to the mining conditions of the 864 working face in T Mine to study the stress evolution, fissure development, and permeability evolution of the coal and rock mass overlying the protective seam mining, especially those near the mining boundary. Results: The overlying coal and surrounding rock mass near the mining boundary are in the state of increasing vertical stress and decreasing horizontal stress, and under this mechanical path of “increasing axial pressure and decreasing peripheral pressure”, the coal mass is damaged and destroyed, fissures are developed, and the permeability is increased; as a result, the coal and surrounding rock mass near the mining boundary mainly produce vertical longitudinal fissures, and the permeability can be increased 900 times compared with that of the overlying coal and surrounding rock mass in the mining boundary. After ground drilling and enhanced depressurization, the measured maximum gas content of the coal mass at the strike boundary is 3.25 m³/t, and the measured maximum gas content of the coal mass at the inclination boundary is 2.63 m³/t. Conclusions: After mining the protective layer, the permeability enhancement effect diminishes from the center toward the sides, yet remains sufficient to eliminate the risk of gas outbursts. This validates the importance of verifying permeability enhancement effects at coal seam boundaries. Full article

Sealing tunnel portals is widely recognized as a pivotal strategy for mitigating fire hazards in tunnel safety management. Nevertheless, the interplay between fire source locations—both longitudinally and transversely—and its impact on flame behavior and ceiling temperature profiles within enclosed structures has not been fully elucidated. Utilizing a 1:15 reduced-scale rectangular tunnel model, this research investigates how varying the fire source position affects the maximum ceiling temperature under enclosed scenarios. Dimensionless parameters, including the longitudinal dimensionless distance D and transverse dimensionless distance Z′, were derived through dimensional analysis. Observations indicate that as the fire approaches the enclosed end, the flame initially leans toward the boundary, peaking in inclination at D = 0.73, and subsequently exhibits a “wall-attached combustion” pattern due to wall confinement. While lateral displacement of the fire source pushes the high-temperature zone toward the corresponding side wall, the longitudinal temperature rise follows a non-monotonic pattern: declining continuously in in Region I (0 ≤ D ≤ 0.73) and rebounding in Region II (0.73 < D < 1). Based on these findings, a dimensionless prediction model incorporating heat release rate (HRR), transverse offset, and longitudinal fire location was developed. Furthermore, a thermal accumulation factor was introduced to refine the predictive model in Region II. The results offer theoretical insights to support fire protection design and risk assessment in enclosed tunnels. Full article

This study employs physical experiments and the RFPA3D numerical method to investigate the fracture evolution of rocks containing a central hole with symmetrically arranged double cracks (seven inclination angles β) under biaxial compression. The results demonstrate that peak stress and strain exhibit nonlinear increases with rising β. Tensile–shear failure dominates at lower angles (β = 0–60°), characterized by secondary crack initiation at defect tips and wing/anti-wing crack development at intermediate angles (β = 45–60°). At higher angles (β = 75–90°), shear failure prevails, governed by crack propagation along hole walls. When β exceeds 45°, enhanced normal stress on crack planes suppresses mode II propagation and secondary crack formation. Elevated lateral pressures (15–20 MPa) significantly alter failure patterns by redirecting the maximum principal stress, causing cracks to align parallel to this orientation and driving anti-wing cracks toward specimen boundaries. Three-dimensional analysis reveals critical differences between internal and surface fracture propagation, highlighting how penetrating cracks around the hole crucially impact stability. This study provides valuable insights into complex fracture mechanisms in defective rock masses, offering practical guidance for stability assessment in underground mining operations where such composite defects commonly occur. Full article

This study investigates the aerodynamic characteristics of drafting cyclists during 45° cornering through numerical simulations, and under the conditions of a vehicle speed of 15 m/s and a 45° body inclination, the SST k-ω turbulence model and grid independence verification (final grid count:12 million) are used to systematically analyze the distribution of velocity, vortex, pressure, and wall shear stress fields. The effects of riding velocity (5–25 m/s) and inter-rider spacing (100–500 mm) on aerodynamic drag were analyzed to reveal the underlying flow mechanisms. The results indicate that as velocity increases, airflow acceleration and boundary-layer shear intensify, leading to enhanced vortex shedding and elevated wall shear stress. In contrast, reduced spacing significantly strengthens wake coupling between riders, effectively lowering the frontal pressure and skin-friction drag of trailing cyclists. The drag reduction rate decreases monotonically with increasing spacing, with the second rider consistently achieving higher aerodynamic benefits than the third rider. Distinct from previous studies that predominantly focus on straight-line motion, this work fills a critical knowledge gap in sports aerodynamics and competitive cycling strategy. By elucidating the unique wake coupling mechanisms induced by body inclination, this study provides scientific evidence for optimizing drafting tactics specifically during high-speed technical cornering. Full article

A plane strain analytical model was developed for the interaction between inclined multilayered rock strata and concrete tunnel lining in deep buried tunnels, with both structures treated as homogeneous isotropic elastic bodies and two contact modes, no-slip and full-slip, considered. A non-iterative complex variable function method was employed, by which analytical challenges in multiply connected domains were overcome and explicit stress and displacement solutions were obtained. Validation was performed through boundary-condition checks and comparative numerical simulations. The results show that under different tangential contact modes, layer inclinations, and lateral pressure coefficients, the stress error on the inner surface of the lining remains in the order of 10⁻² Pa. The stress and displacement components on both sides of each interface satisfy the associated continuity conditions with excellent agreement. The proposed analytical method nearly perfectly satisfies all boundary and continuity conditions. Under non-hydrostatic loading conditions, the numerical and analytical results for different tangential contact modes also show excellent agreement. The von Mises stress errors are generally controlled within 0.03 MPa, and the maximum relative error—located near the inner surface of the lining—remains below 4%, while displacement errors stay below 0.2 mm. Interface stress jumps are accurately captured and oscillations in zones with high stiffness contrast are effectively avoided. The method is presented as a fast and reliable analytical tool for tunnel design under complex multilayered rock conditions. Full article

This research employs a Caputo fractional-derivative model to investigate the effects of magnetic field inclination and thermal radiation on the unsteady flow of a Casson fluid over an inclined plate in a porous medium. The model incorporates memory effects to generalize the classical formulation, while also accounting for internal heat generation and a chemical reaction. The governing equations are solved analytically using the Laplace transform, yielding power-series solutions in the time domain. Convergence analysis and benchmarking confirm the reliability and accuracy of the derived solutions. Key physical parameters are analyzed, and their impacts on the system are presented both graphically and in tabular form. The results indicate that increasing the inclination of the plate and magnetic field significantly suppresses the velocity distribution and reduces the associated boundary-layer thickness. Conversely, a higher fractional-order parameter enhances the velocity, temperature, and species concentration profiles by reducing memory effects. This study makes a significant contribution to the fractional modeling of unsteady heat and mass transfer in complex non-Newtonian fluids and provides valuable insights for the precise control of transport processes in industrial, chemical, and biomedical applications. Full article

In the present study, numerical simulations were conducted to investigate the behavior of a 60° inclined dense jet discharged onto horizontal (0°) and sloped (5°) bottoms in a stagnant environment. The objective was to evaluate the capability of Large Eddy Simulation (LES) in capturing both the kinematic and mixing characteristics of inclined dense jets interacting with different bottom boundaries. A Reynolds-Averaged Navier–Stokes (RANS) model was also included for comparison. The LES simulations successfully reproduced the key kinematic and mixing characteristics, including the jet trajectory, centerline peak location, impact point, and terminal rise height, and showed strong agreement with the experimental observations. LES also predicted the concentration distributions and variations along both the horizontal and sloped bottoms, whereas the RANS model tended to underestimate both geometrical and dilution properties. A Gaussian fitting function was proposed to estimate the concentration distribution under both bottom conditions. Analysis of the spreading layer indicated that the concentration profiles exhibited self-similarity. Energy spectrum analysis showed that the sloped bottom enhanced shear-induced turbulence, thereby improving the mixing efficiency. Results confirm the reliability of LES for describing jet–bed interactions and emphasize the influence of bed slope on jet dilution and mixing behavior. Full article

Consumer digital hoarding is becoming increasingly common in agricultural live social e-commerce, where the abundance of product information, seasonal promotions, and origin-based narratives make consumers more inclined to accumulate digital content such as product links, coupons, and live-stream screenshots. This phenomenon not only affects consumers’ digital mental health, consumption behavior, and decision-making ability, but also poses challenges to agricultural merchants and platforms in terms of customer conversion, precision marketing, and supply chain management. Drawing on the SOR model and integrating construal level theory, this paper constructs a research framework to analyze the key factors influencing consumers’ willingness to digitally hoard in the context of agricultural live social e-commerce. Based on a questionnaire survey of 322 consumers, and using the Ordered Probit (O-Probit) model, the empirical results show that emotional interaction significantly influences digital hoarding intention through the chain mediating effects of emotional attachment and fear of missing out (FOMO). Furthermore, social distance and immersion serve as boundary conditions in this mechanism. Our findings not only deepen the understanding of consumer digital hoarding behavior in agricultural live e-commerce, but also provide new insights for agricultural merchants and platforms to better design interaction strategies, balance consumers’ digital accumulation with actual purchasing conversion, and enhance the efficiency of agricultural product marketing. Full article