Explore the vast range of titles available.

Selection for divergent performance optima has been proposed as a central mechanism underlying adaptive radiation. Uncovering multiple optima requires identifying forms associated with different adaptive zones and linking those forms to performance. However, testing and modeling the performance of complex morphologies like the cranium is challenging. We introduce a three-dimensional finite-element (FE) model of the cranium that can be morphed into different shapes by varying simple parameters to investigate the relationship between two engineering-based measures of performance, mechanical advantage and von Mises stress, and four divergent adaptive zones occupied by New World Leaf-nosed bats. To investigate these relationships, we tested the fit of Brownian motion and Ornstein–Uhlenbeck models of evolution in mechanical advantage and von Mises stress using dated multilocus phylogenies. The analyses revealed three performance optima for mechanical advantage among species from three adaptive zones: bats that eat nectar; generalized insectivores, omnivores and some frugivores; and bats that specialize on hard canopy fruits. Only two optima, one corresponding to nectar feeding, were consistently uncovered for von Mises stress. These results suggest that mechanical advantage played a larger role than von Mises stress in the radiation of New World Leaf-nosed bats into divergent adaptive zones.

We propose a new approach for railway path diagnostics on the basis of track line stress–strain analysis using the data provided by high-precision accelerometers. This type of sensor provides sufficient accuracy with lower costs, and enables the development of a railway digital twin, according to the concept of the Internet of Things. The installation of sensors on a railway track along its entire length allows real-time monitoring of the states of the technical parameters of the railway track, and using mathematical methods to evaluate its wear on the basis of constantly received data. This paper presents an original 3D model of a railway track line and the results of its analysis using a finite element method. To test the model, we performed an analysis of the normal stresses and deformations in the elements of a railway track by simulating the impact of rolling stock on a section of a railway track with intermediate rail fastenings, ZhBR-65SH. The research results were probated and tested at the testing ground of the Kuibyshev branch of Russian Railways, the Samara track. The proposed approach makes it possible to determine the load of the track, and knowing the movement of the rail, to calculate the structural stress in the elements of the railway track, to constantly monitor the parameters of the slope and rail subsidence.

Objectives This study used three‐dimensional (3D) finite‐element analysis (FEA) to investigate the effect of different implant placement strategies on the biomechanical behavior of implant‐supported maxillary overdentures, and provide an initial guide to clinical treatment. Materials and Methods For an edentulous maxilla, six different implant‐supported overdenture models with various implant placement strategies were created using CATIA software. The reference model (5R‐3R‐3L‐5L) featured symmetrical implant placement in the canine and second premolar regions bilaterally. Five additional models incorporated asymmetrical implant placement strategies: 5R‐3R‐1L‐3L, 5R‐2R‐3L‐5L, 5R‐4R‐3L‐5L, 4R‐3R‐3L‐5L, and 6R‐3R‐3L‐5L. All models had identical bone properties, prosthetic components, material characteristics, and loading conditions. The geometric models were analyzed using ANSYS 24.0 Workbench software. The maximum principal stress for bone, and stress distribution patterns were analyzed, and the performance of the models was compared with the symmetrical reference model. Results The quantitative and qualitative results showed that the implant placement strategy significantly influenced the magnitude and distribution of stress. The symmetrical implant placement strategy demonstrated the most favorable stress distribution, with the lowest maximum stress values in positions 5 R (2.69 MPa), 3 R (2.25 MPa), 3 L (2.16 MPa), and 5 L (3.24 MPa). Placement of implants in the anterior region resulted in stress concentration in the anterior region with maximum stress values at positions 5 R (3.24 MPa), 3 L (3.96 MPa), 1 L (5.09 MPa), and 3 L (5.57 MPa). Asymmetrical implant placement strategies with increased anteroposterior distribution and more posterior placement also demonstrated favorable biomechanical performance. Certain asymmetrical patterns induced fulcrum effects, leading to heterogeneous stress distribution. Conclusions The symmetrical (5R‐3R‐3L‐5L) implant placement may provide a more uniform stress distribution, which may enhance peri‐implant bone preservation and long‐term implant stability. Implant placement in the canine region should be prioritized, while mesially‐positioned implants warrant clinical caution due to higher stress levels in bilaterally symmetrical implant placement strategies.

Determination of earth pressures is one of the fundamental tasks in geotechnical engineering. Although many different methods have been utilized to present passive earth pressure coefficients, the influence of non-associated plasticity on the passive earth pressure problem has not been discussed intensively. In this study, finite-element limit analysis and displacement finite-element analysis are applied for frictional materials. Results are compared with selected data from literature in terms of passive earth pressure coefficients, shape of failure mechanism and robustness of the numerical simulation. The results of this study show that passive earth pressure coefficients determined with an associated flow rule are comparable to the Sokolovski solution. However, comparison with a non-associated flow rule reveals that passive earth pressure coefficients are significantly over predicted when following an associated flow rule. Moreover, this study reveals that computational costs for determination of passive earth pressure are considerably larger following a non-associated flow rule. Additionally, the study shows that numerical instabilities arise and failure surfaces become non-unique. It is shown that this problem may be overcome by applying the approach suggested by Davis (Soil Mech 341–354, 1968).

Modelling for very fast transients (VFTs) requires good knowledge of the behaviour of gas insulated substation (GIS) components when subjected to high frequencies. Modelling usually takes the form of circuit-based insulation coordination type studies, in an effort to determine the maximum overvoltages and waveshapes present around the system. At very high frequencies, standard transmission line modelling assumptions may not be valid. Therefore, the approach to modelling of these transients must be re-evaluated. In this work, the high frequency finite element analysis (FEA) was used to enhance circuit-based models, allowing direct computation of parameters from geometric and material characteristics. Equivalent models that replicate a finite element model’s frequency response for bus-spacer and 90° elbow components were incorporated in alternative transients program-electromagnetic transients program (ATP-EMTP) using a pole-residue equivalent circuit derived following rational fitting using the well-established and robust method of vector fitting (VF). A large model order is often required to represent this frequency dependent behaviour through admittance matrices, leading to increased computational burden. Moreover, while highly accurate models can be derived, the data extracted from finite element solutions can be non-passive, leading to instability when included in time domain simulations. A simple method of improved stability for FEA derived responses along with a method for identification of a minimum required model order for stability of transient simulations is proposed.

Objective Inferior pole patellar fractures (IPPFs) pose a significant challenge due to their complex fracture patterns and high risk of complications associated with current treatment methods. This study aims to (1) characterize the fracture patterns of IPPFs using fracture mapping and (2) compare the biomechanical stability and clinical outcomes of treatment with anchor suture with patellar cerclage versus Kirschner‐wire tension band combined with patellar cerclage. Methods (1) A retrospective analysis was conducted on 61 patients with IPPF. For each case, fracture reduction was manually simulated, with fracture lines and fragments overlaid onto a complete patella template to identify fracture patterns. (2) Finite‐element models were used to analyze the mechanical properties of anchor suture and titanium cable cerclage treatment and Kirschner‐wire tension band combined with patellar cerclage in treating IPPFs. Additionally, a retrospective analysis of clinical data was performed on 57 patients with IPPF (AO/OTA 34 A1) treated at our institution between January 1, 2023, and December 25, 2023. Of these, 18 patients underwent anchor suture and titanium cable cerclage (Group A), and 39 underwent Kirschner‐wire tension band combined with patellar cerclage (Group B). We compared operative time, final knee range of motion, incidence of secondary surgery, postoperative complications, and functional recovery between the two groups based on medical records and follow‐up results. Results (1) IPPFs were predominantly comminuted, with fracture lines on the anterior view concentrated laterally and near the superior surface of the inferior pole. Fracture lines became more sparse as they approached the distal patella. The posterior view was similar to the anterior, with the majority of fractures near the superior surface of the inferior pole. (2) Finite‐element analysis revealed no significant differences between the two groups in terms of displacement and stress. Operative time was similar between the groups (p > 0.05), as were final knee range of motion (p > 0.05) and postoperative Bostman scores (p > 0.05). Group A had no postoperative complications or readmissions, while Group B had two cases of hardware irritation and one case of knee joint infection. Conclusion The fracture lines of IPPF are varied, often comminuted, and correlate with the mechanism of injury. Biomechanical and clinical outcomes suggest that anchor suture with patellar cerclage is a viable option for stabilizing IPPF. Trial Registration: ClinicalTrials.gov identifier: NCT06736639 This study characterizes the fracture patterns of inferior pole patellar fractures (IPPFs) and compares the clinical outcomes of anchor suture with titanium cable cerclage versus Kirschner‐wire tension band. Finite‐element analysis and clinical results indicate that anchor suture with cerclage provides stable fixation and is associated with fewer postoperative complications.

Purpose Guided endodontics allows precise access in challenging cases such as calcified canals; however, drilling can generate temperature increases that risk damaging periradicular tissues. This study aimed to evaluate the influence of different sleeve materials—zirconia, cobalt‐chromium (CoCr), and titanium—on temperature changes during guided endodontic access using finite‐element analysis (FEA). Materials and Methods High‐resolution three‐dimensional (3D) models of a human central incisor and titanium sleeve were developed using micro‐computed tomography (micro‐CT), 3D Slicer, Meshmixer, and SolidWorks. FEA simulations were conducted in Abaqus under a 2° deviation and 700 rpm drilling, with thermal properties based on literature. Experimental validation employed thermocouples to determine the temperature changes under identical conditions. Results Results showed that zirconia sleeves produced the lowest temperature elevation (< 10°C) with localized concentration, while CoCr and titanium allowed more even heat dissipation. Conclusion Zirconia is an effective insulator due to its thermal conductivity properties. CoCr has emerged as a promising alternative to titanium, offering more favorable thermal and mechanical characteristics.

Steels are preferred in the building of commercial ships because they can be easily welded and supplied. Although it varies according to the parts of the ships, it is known that high-strength steels are preferred especially in bulb and side coatings where relatively high strength is desired during the building process. In the process of welding these steels, mostly gas and submerged arc welding are used. On the other hand, studies continue for the use of the new generation friction stir welding (FSW), which is known to have many advantages over existing welding methods, in the shipbuilding process. The formability of the welded plates in the construction process of the ships is extremely important to give the necessary form to the ship. On the other hand, post-weld formability properties are of great importance for determining the strength and elongation values in wave crests and wave troughs to which ships are exposed during navigation. In this context, in this study, relatively high-strength AH32 shipbuilding steel was joined with FSW and the formability behavior of the welded region was investigated comparatively by experimental, finite element analysis and artificial neural network methods. As a result of the studies, it was determined that the strength values in the weld zone of the steel joined by FSW increased compared to the pre-weld and the formability behavior did not deteriorate. In addition, it was determined that the results of finite element analysis and artificial neural networks were extremely consistent with the experimental data, and it was determined that the models created in the study would give close results to the real results even without experimental studies.

The determination of the factor of safety (FoS) of slopes during seismic excitation can be complex if the relevant effects of pore water pressure accumulation, nonlinear material response and variable shear strength are duly accounted for. A rational two-step approach to tackle this task based on a hydro-mechanically coupled dynamic simulation and finite element limit analyses is henceforth introduced. To ensure accurate transfer of the hydro-mechanical soil state, a mapping concept is presented, accounting for spatial distributions of stresses, excess pore water pressures, inertial forces and shear strength. The proposed approach is compared to limit equilibrium method (LEM) for the case of a large-scale water-saturated open cast mine slope subjected to seismic loading. In comparison with LEM, the new approach to assess seismic slope stability proves to be simpler in its implementation and straightforward, which could be an important asset for practitioners.

New methods are needed in microsystems technology for evaluating microelectromechanical systems (MEMS) because of their reduced size. The assessment and characterization of mechanical and structural relations of MEMS are essential to assure the long-term functioning of devices, and have a significant impact on design and fabrication. Within this study a concept for the investigation of mechanically loaded MEMS materials on an atomic level is introduced, combining high-resolution X-ray diffraction (HRXRD) measurements with finite element analysis (FEA) and mechanical testing. In situ HRXRD measurements were performed on tensile loaded single crystal silicon (SCSi) specimens by means of profile scans and reciprocal space mapping (RSM) on symmetrical (004) and (440) reflections. A comprehensive evaluation of the rather complex XRD patterns and features was enabled by the correlation of measured with simulated, 'theoretical' patterns. Latter were calculated by a specifically developed, simple and fast approach on the basis of continuum mechanical relations. Qualitative and quantitative analysis confirmed the admissibility and accuracy of the presented method. In this context [001] Poisson's ratio was determined providing an error of less than 1.5% with respect to analytical prediction. Consequently, the introduced procedure contributes to further going investigations of weak scattering being related to strain and defects in crystalline structures and therefore supports investigations on materials and devices failure mechanisms.