Search Results (195)

This paper presents results from statistical tests on random parameters of strength properties of steel used to manufacture corrugated webs for SIN plate girders, depending on the place of specimen cut-out, that is, from the flat section or ridge of the wave. The tests were performed on specimens collected from 12 randomly selected corrugated sheets with thicknesses of 2, 2.5 and 3 mm, provided by the manufacturer of SIN beams. The analysis was used to select variation coefficients of yield strength V_Re = D(R_e)/E(R_e) and partial coefficients of yield strength γ_m for steel in flat and arched parts of the web. Metallographic and Vickers hardness tests were performed. Values of deformations and residual stresses were determined. The close correlation between the influence of the web plate shape and the strength parameters along the web curvature was demonstrated. Analysis of the initiation points of stability loss (IPLS points) revealed that the initiation of stability loss occurs in the area of the flat web sections. In addition to the influence of geometry, the influence of the change in yield strength, as identified in this paper, can be observed. Consideration of random features of yield strength and web thickness can lead to modifications in designing and calculating structures made of SIN girders. Full article

Background: Reverse-oblique femoral fractures are regarded as highly unstable and are still associated with high complication and failure rates. A new classification system is said to facilitate risk assessment and decision-making. Methods: Over ten years, 7804 patients with per/subtrochanteric fractures were screened in this retrospective analysis. A total of 552 patients with a reverse-oblique fracture pattern were included. The fractures were classified according to the new classification system. The choice of implants, complication rates, revision surgery, and time of surgery were recorded. Radiological outcome parameters and dislocation were measured. Results: For the classification, a good intra-rater reliability (r = 0.77) and inter-rater reliability (k = 0.64) were calculated. The complication rate was overall 19% (n = 105). More than 60% of complications needed revision surgery. The most common complications were cut-out and implant failure (3%); only Parker’s ratio, as a radiological parameter, had prognostic value. Malreduction had a negative impact on mal- or non-unions (p < 0.01), and a trend towards higher overall complications (p = 0.52). Prolonged time of surgery increased the overall complication rate (r = 0.2, p < 0.001). The same was found after open reduction (p = 0.005, OR 2.00). The use of cerclage wires had no positive or negative effects. The use of short or long implants did not influence the outcome. Conclusions: Reverse-oblique femoral fractures are associated with a high complication rate. Short implants can be safely used in cases without severe dislocation if a sufficient working length is considered. Anatomical reduction benefits the outcome as long as it can be performed closed. The classification system presents good inter- and intra-rater reliability. Full article

Background: Complications after proximal humerus osteosynthesis are not uncommon. The aim of this study was to compare the outcomes of osteosynthesis using PHILOS with fresh-frozen femoral head allograft augmentation and without it, and to assess the influence of risk factors and their impact on the occurrence of postoperative complications. Methods: This retrospective study evaluates the radiological outcomes and complications of treating proximal humerus fractures (Neer III–IV) in 116 patients over 50 years of age treated between 2017 and 2021. Results: Osteosynthesis without allograft was performed in 84 patients and with allograft in 32 patients. In total, 42 patients (36%) had a three-part fracture and 74 (64%) had a four-part fracture. The Deltoid Tuberosity Index was comparable between the groups (1.59 ± 0.25 vs. 1.50 ± 0.26; p = 0.802). The average duration of surgery was 101.3 ± 21.3 min with allograft and 86.0 ± 31.9 min without allograft (p = 0.004). AVN was verified in four patients (3.5%), head collapse in nine (8%), cut-out in six (5%), reoperation in eight (7%), infection in three (2.5%), and pseudoarthrosis in one (1%) case. Conclusions: An allograft augmentation improves construct stability, but cannot compensate for inadequate surgical technique. None of the risk factors significantly influenced the development of AVN and pseudoarthrosis. The greater tubercle comminution (p = 0.005), calcar loss (p = 0.020, p = 0.112), allograft augmentation (p < 0.001), and medial hinge restoration (p = 0.012, p = 0.002) were significant risk factors associated with HC and screw cut-out, respectively. The greater tubercle redislocation was influenced by its comminution, calcar loss, and the use of allograft augmentation. HFZ and DTI had no significant impact on surgery results or complications. Full article

Background and Objectives: Screw cut-out is the most common mechanical complication after intertrochanteric fracture fixation with proximal femoral nails (PFNs). While the traditional tip–apex distance (TAD) is widely used, the calcar-referenced TAD (CalTAD) may better represent inferomedial cortical support. This study aimed to identify radiographic predictors of cut-out in dual-screw PFN fixations and establish a clinically relevant threshold for inferior-screw-based CalTAD. Materials and Methods: A retrospective cohort of patients treated with a dual cephalic screw PFN between 2017 and 2024 was analyzed. The implant uses two equal-diameter screws. Radiographic parameters included TAD, inferior-screw CalTAD, reduction quality, lateral wall thickness (LWT), collodiaphyseal angle (CDA), and Cleveland zone positioning. Logistic regression analyses were used to identify independent predictors of mechanical failure. Results: Both TAD and CalTAD values were significantly higher in patients who experienced screw cut-out. ROC analysis identified an inferior-screw-referenced CalTAD cutoff with strong predictive accuracy (AUC = 0.84). Optimal screw positioning, particularly avoiding superior placement on AP radiographs, was associated with reduced cut-out risk, while anterior positioning on the lateral view demonstrated only a borderline effect. Reduction quality showed borderline significance in univariate testing but remained independently predictive in multivariate modeling, while LWT and CDA were not significantly different between groups. Conclusions: Ensuring the inferior lag screw is positioned close to the calcar and achieving a low CalTAD, together with proper Cleveland zone alignment, appear to be key technical goals for minimizing mechanical cut-out in dual-screw PFN fixations. These findings support the use of inferior-screw–referenced CalTAD as a reliable and reproducible parameter for surgical optimization. Full article

Accurate prediction of wind turbine power output is essential for optimizing renewable energy generation, enhancing grid integration, and improving the efficiency of wind farms. However, the inherent non-linearities of wind speed–power relationships, combined with abrupt cut-in, rated, and cut-out effects, pose a significant modeling challenge. In this study, we investigate the use of artificial neural networks (ANNs) to model the power curve of a $1\mathrm{kW}$ wind turbine, using an open-access dataset of real operational measurements recorded at 10 min intervals over the course of 2011. In particular, we compare a conventional multilayer perceptron (MLP) trained on raw wind speed inputs with a Fourier-feature-encoded MLP designed to mitigate spectral bias—the tendency of neural networks to favor smooth, low-frequency patterns over sharp, high-frequency variations. Experimental results show that the Fourier-enhanced MLP substantially improves predictive performance, reducing the mean absolute error (MAE) by more than $65\%$ and achieving an $R^2$ score of $0.999$. The proposed approach demonstrates that Fourier feature encoding enables neural networks to capture sharp non-linearities in wind-turbine power curves, representing one of the first applications of this technique to wind-turbine power-curve modeling. Full article

Conventional wind resource assessments often fail to capture the complex interaction between topography and technology suitability in mountainous regions. This study employs a 40-year, 5 km resolution WRF dataset to construct a differentiated assessment framework for Sichuan Province, distinguishing between utility-scale and distributed generation potentials. The results reveal that topography dictates a stark west-to-east resource gradient, with the Extreme Wind (EW) region possessing a wind power density (1166 W/m²) exceeding that of the sheltered Basin by over 24 times. However, this high potential is coupled with severe operational risks, as overspeed shutdown durations (>25 m/s) in the EW region exceed those in the High Wind Plateau by more than 4.45 times. Crucially, shifting to a distributed generation perspective (2–15 m/s) fundamentally reconstructs the resource landscape: the Basin gains a substantial “light breeze dividend” with available hours increasing by ~89%, whereas the EW region suffers a “high-speed penalty” of ~7% due to frequent cut-out events. Despite a systematic model bias attributed to the “representativeness mismatch” between ridge-resolving grids and valley-bottom observations, the revealed relative spatiotemporal patterns remain robust. Full article

Rapid and precise intervention in disaster and medical-aid scenarios demands aerial platforms that can both survey and physically interact with their environment. This study presents the design, fabrication, modeling, and experimental validation of a one-piece, 3D-printed quadcopter with an integrated six-degree-of-freedom aerial manipulator robotic arm tailored for emergency response. First, we introduce an ‘X’-configured multi-rotor frame printed in PLA+ and optimized via variable infill densities and lattice cutouts to achieve a high strength-to-weight ratio and monolithic structural integrity. The robotic arm, driven by high-torque servos and controlled through an Arduino-Pixhawk interface, enables precise grasping and release of payloads up to 500 g. Next, we derive a comprehensive nonlinear dynamic model and implement an Extended Kalman Filter-based sensor-fusion scheme that merges Inertial Measurement Unit, barometer, magnetometer, and Global Positioning System data to ensure robust state estimation under real-world disturbances. Control algorithms, including PID loops for attitude control and admittance control for compliant arm interaction, were tuned through hardware-in-the-loop simulations. Finally, we conducted a battery of outdoor flight tests across spatially distributed way-points at varying altitudes and times of day, followed by a proof-of-concept medical-kit delivery. The system consistently maintained position accuracy within 0.2 m, achieved stable flight for 15 min under 5 m/s wind gusts, and executed payload pick-and-place with a 98% success rate. Our results demonstrate that integrating a lightweight, monolithic frame with advanced sensor fusion and control enables reliable, mission-capable aerial manipulation. This platform offers a scalable blueprint for next-generation emergency drones, bridging the gap between remote sensing and direct physical intervention. Full article

Background and Objectives: Intertrochanteric femur fractures are very common, especially in the elderly population, and cause serious morbidity and mortality. Today, the most commonly used implants in the treatment of these fractures are proximal femoral nails (PFNs). This study aimed to analyze the clinical and radiological results of patients who underwent surgical treatment with a proximal femoral nail (PFN) for intertrochanteric femur fractures and later required revision surgery for various reasons. Materials and Methods: Patients who underwent surgical treatment PFN due to intertrochanteric femur fractures between 2022 and 2025 were included in the study, and the patients were divided into revision and non-revision groups. Demographic information, postoperative radiological measurements, complications, and reasons for revision surgery were noted, and risk factors leading to revision were determined using bivariate and multivariate analyses. Results: A total of 207 patients, 97 revision (46.9%) and 110 non-revision (53.1%), were included in this study. Cut-out was identified as the most common revision cause (n = 52, 53.6%), followed by loss of reduction (n = 15, 15.5%), implant failure (n = 14, 14.4%), nonunion (n = 6, 6.2%), infection (n = 4, 4.1%), cut-through (n = 3, 3.1%), and avascular necrosis of the femoral head (n = 3, 3.1%). When bivariate analysis was performed to identify risk factors for revision, it was observed that female gender (p = 0.004), presence of posteromedial comminution (p < 0.001), operation under spinal anesthesia (p = 0.023), surgery in supine position (p < 0.001), using closed reduction techniques (p < 0.001), presence of infection (p = 0.004), and higher Charlson comorbidity index values (p < 0.001) increased the risk of revision. Additionally, positive and neutral medial cortex support (p < 0.001) decreased the risk of revision. Multivariate analysis was also applied to the parameters found to be significant in bivariate analysis. As a result of this analysis, surgery in the supine position (p < 0.001), using closed reduction techniques (p < 0.001), and higher Charlson comorbidity index values (p < 0.001) remained significant. Conclusions: Careful evaluation of the fracture morphology, ensuring optimal reduction, and considering the accompanying comorbidities of the patients in the surgical planning of unstable trochanteric fractures stand out as key elements in increasing surgical success. Full article

Diabetic foot ulcers (DFUs) are a serious complication of diabetes and a leading cause of lower-limb amputations. Excessive plantar pressure in high-risk regions such as the heel and forefoot contributes significantly to their development. This study presents the design, simulation, and three-dimensional prototyping of customised diabetic insoles aimed at redistributing pressure and reducing ulcer risk. Insole models are created in Autodesk Inventor, evaluated with finite element analysis (FEA) in ANSYS Workbench, and fabricated using 3D printing technology. Three designs are evaluated, i.e., a standard insole, a circular-cutout insole, and an irregular-cutout insole, using four different materials, i.e., Ethylene Vinyl Acetate (EVA)1, EVA2, EVA3, and polyurethane (PU). Under applied pressure of 0.3 MPa by a diabetic foot, a customised EVA1 insole reduces barefoot peak stress from 3.97 MPa to 1.51 MPa (61.96% reduction), while irregular isolations lower ulcer-rim stress from 0.87 MPa to 0.63 MPa (27.8% reduction). EVA-based insoles outperformed the PU one, and prototypes are successfully printed in EVA and PU, demonstrating feasibility for low-cost and patient-specific applications. Full article

Generating realistic and diverse driving scenarios is essential for effective scenario-based testing and validation in autonomous driving and the development of driver assistance systems. Traditionally, parametric models are used as standard approaches for scenario generation, but they require detailed domain expertise, suffer from scalability issues, and often introduce biases due to idealizations. Recent research has demonstrated that AI models can generate more realistic driving scenarios with reduced manual effort. However, these models typically focused on single scenario types, such as cut-in maneuvers, which limits their applicability to diverse real-world driving situations. This paper, therefore, proposes a unified generative framework that can simultaneously generate multiple types of driving scenarios, including cut-in, cut-out, and cut-through maneuvers from both directions, thus covering six distinct driving behaviors. The model not only learns to generate realistic trajectories but also reflects the same statistical properties as observed in real-world data, which is essential for risk assessment. Comprehensive evaluations, including quantitative metrics and visualizations from detailed latent and physical space analyses, demonstrate that the unified model achieves comparable performance to individually trained models. The shown approach reduces modeling complexity and offers a scalable solution for generating diverse, safety-relevant driving scenarios, supporting robust testing and validation. Full article

Background: Cephalomedullary nails are the standard treatment of trochanteric fractures, and some implants with a perforated blade allow augmentation with bone cement to increase mechanical stability. The study compares the results of PFNA and TFNA implants (DePuy Synthes) with or without cement augmentation of the blade. Methods: A retrospective study evaluated 219 trochanteric fractures. The study included 59 men (27%) and 160 women (73%), with a mean patient age of 82 years. The most common fractures were type 31A2 (56%), followed by type 31A1 (25%) and type 31A3 (19%). The monitored parameters were evaluated from anteroposterior and axial images of the proximal femur and pelvis. TAD, blade position, lateral blade prominence, fracture varus, and cut-out were evaluated. Results: Cement-augmented blade implants (CABs) in 68 patients (31%) and cement-free implants (NCABs) in 151 patients (69%) were used. The average age difference between the groups was 7 years (CAB 86.07 ± 5.85 and NCAB 79.13 ± 8.48). CABs were used more frequently in women (60 cases) than in men (8 cases). Blade position was optimal in 68% of cases and suboptimal in 32%. The risk of varus deformities was not statistically significantly affected by the blade position. The statistical significance of CABs for reducing the risk of varus deformities in stable fractures (p = 0.396) or unstable fractures (p = 0.101) was not confirmed. The average varus angulation during treatment was 2.57° (CAB 2.53° and NCAB 2.67°). A varus deformity greater than 10° was confirmed in 8 eight patients (3.7%) and cut-out in three patients (1.4%). All patients with cut-out were in the NCAB group. Cement leakage occurred in two cases and was asymptomatic. One case of deep infection, lateral blade prominence, and avascular necrosis (AVN) were recorded. Conclusions: Cement augmentation of the blade did not significantly reduce varus deformity in this cohort, regardless of blade position of fracture stability. CABs may prevent cut-out in specific subgroups, but this requires further investigation. Full article

Due to the random factors that influence grinding stability, hardness distribution appears in inhomogeneity at different locations on the hardened layer in grind-hardening technology. It may affect the wear resistance of parts. Therefore, in order to explore the influence mechanism of hardness homogeneity on the wear resistance comprehensively, grind-hardening and friction experiments on AISI 1045 steel are carried out. Then, the causes of inhomogeneous hardness distribution are analyzed, and the influence of hardness homogeneity on wear resistance is also discussed. Combining the Archard wear model, the wear process of the hardened layer is simulated for analyzing the effect of contact stress distribution and action range on material loss in the worn area and finally realizing the prediction of the wear depth. The results show that the difference in microstructure distribution caused by the nonlinear variation in grinding force is the fundamental reason for the hardness inhomogeneity of the hardened layer. The hardness homogeneity results in the wear resistance of the cut-out end being superior to that of cut-in end. Additionally, the error between the predictive and the experimental value of the wear depth with different parameters is between 3.6% and 11.3%, thereby verifying the effectiveness of the theoretical research. Full article

Background/Objectives: Anterior redisplacement, defined as a postoperative anterior shift of the distal fragment despite intraoperative reduction, is occasionally observed after cephalomedullary nailing for trochanteric femoral fractures. However, its incidence and associated risk factors remain unclear. This study aimed to determine the incidence of anterior redisplacement following intramedullary nail fixation in geriatric trochanteric fractures, and to identify independent risk factors. Methods: This study retrospectively reviewed data from 598 consecutive hips in 577 patients (aged ≥65 years) who underwent intramedullary nail fixation for trochanteric fractures at a single center (2012–2023). Sagittal reduction on the lateral radiographic view was classified as posterior, anatomical, or anterior according to the position of the distal fragment, and was recorded preoperatively and postoperatively. Anterior redisplacement, the primary outcome, was defined as a change in alignment from a posterior or anatomical position postoperatively to an anterior position on any subsequent follow-up radiograph. Independent risk factors were identified by logistic regression. Results: Among the 543 hips reduced posteriorly (n = 204) or anatomically (n = 339), anterior redisplacement occurred in 73 (13.4%). The incidence of anterior redisplacement was significantly higher following anatomical compared to posterior reduction (19.5% vs. 3.4%; p < 0.001), and also higher in fractures that were anteriorly aligned preoperatively (18.0%) compared to anatomical (8.5%; p < 0.01) and posterior (6.2%; p < 0.01) alignment. Multivariate analysis revealed two independent predictors: preoperative anterior alignment (odds ratio [OR] 1.87, 95% confidence interval [CI] 1.24–2.81; p = 0.003) and postoperative anatomical (vs. posterior) reduction (OR 6.49, 95% CI 2.92–14.44; p < 0.001). Age, sex, Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association classification, Evans–Jensen classification, nail length, and canal-filling ratio were not associated with redisplacement. No lag-screw cutout occurred during the follow-up. Conclusions: Anterior redisplacement occurred in one of seven geriatric trochanteric fractures despite apparently satisfactory fixation. An anatomical sagittal reduction—traditionally considered “ideal”—increases the risk more than sixfold, whereas a deliberate posterior-buttress is protective. Unlike patient-related risk factors, sagittal reduction is under the surgeon’s control. The study findings provide evidence that choosing a slight posterior bias can significantly improve stability. Full article

Background/Objectives: Trochanteric femoral fractures pose significant surgical challenges, particularly in elderly patients. Intramedullary nailing (IMN) and plate fixation (PF) are the primary operative strategies, yet their comparative efficacy and safety remain debated. This meta-analysis synthesizes randomized controlled trials (RCTs) to evaluate clinical, functional, perioperative, and biomechanical outcomes of IMN versus PF specifically in trochanteric fractures. Methods: A systematic search of six databases was conducted up to 20 May 2024, to identify RCTs comparing IMN and PF in adult patients with trochanteric femoral fractures. Data extraction followed PRISMA guidelines, and outcomes were pooled using random-effects models. Subgroup analyses examined the influence of fracture stability, implant type, and patient age. Risk of bias was assessed using the Cochrane RoB 2.0 tool. Results: Fourteen RCTs (n = 4603 patients) were included. No significant differences were found in reoperation rates, union time, implant cut-out, or mortality. IMN was associated with significantly reduced operative time (MD = −5.18 min), fluoroscopy time (MD = −32.92 s), and perioperative blood loss (MD = −111.68 mL). It also had a lower risk of deep infection. Functional outcomes and anatomical results were comparable. Subgroup analyses revealed fracture stability and nail type significantly modified operative time, and compression screws were associated with higher reoperation rates than IMN. Conclusions: For trochanteric femoral fractures, IMN and PF yield comparable results for most clinical outcomes, with IMN offering some advantages in surgical efficiency and perioperative morbidity, though functional outcomes were comparable. Implant selection and fracture stability influence outcomes, supporting individualized surgical decision making. Full article

Intertrochanteric fractures in the elderly present complex challenges due to poor bone quality and comorbidities. Cephalomedullary (CM) nails offer biomechanical advantages that support early mobilization, yet complications such as cutout, implant failure, and malalignment persist. This review examines the effectiveness of CM nail fixation in geriatric extracapsular hip fractures and introduces the RESCUE technique—a structured, mnemonic-based approach aimed at improving surgical outcomes and reducing common complications. RESCUE stands for Reduce, Entry point, Screw, Compress, Unleash traction, and Enhance full-weight bearing. This six-step framework addresses the critical elements of fixation, including precise reduction, optimal entry point selection, central screw placement, controlled fracture compression, cautious traction management, and early mobilization. Case illustrations of frequent failure patterns underscore the practical application of the RESCUE technique. By following this systematic approach, surgeons can enhance construct stability, minimize failure risk, and promote functional recovery in elderly patients. Full article