Search Results (400)

The squat exercise is one of the most widely practiced globally, prompting an investigation into the interplay among dimensional (particularly body height, BH), kinematic, and kinetic metrics. The study involved physically active men (n = 18, age: 23.8 ± 5 years, BH: 177.3 ± 10 cm, body mass: 78.1 ± 9 kg, body mass index: 24.9 ± 2.3 kg/m², at least 6 months of squat training experience). They performed five squat repetitions (hands at midwaist) while being recorded with a Basler camera (100 Hz, sagittal plane) to estimate kinematic metrics (segmental inclination and joint angles at the lowest descending position), in synchronization with vertical ground reaction force and center of pressure recording (forceplate 1000 Hz, Kistler Type-9286AA, Bioware v. 5.5.1.0 software). Statistical analysis (SPSS 30.0, p ≤ 0.05) included one-way ANOVA to test the BH effect and allometric analysis to produce scaling exponents for the squat performance indices (Force, Leverage, and Stability Index) used to rank participants’ performance efficiency while neutralizing the influence of body size. The body-dimensional metrics differed significantly among the 3 BH groups, except for segmental proportions (p > 0.05). Apart from the more upright shank (about 6 degrees) in the Tall than in the Medium and Short BH groups (p < 0.05), no significant BH effect was observed in the kinematic and kinetic metrics (p > 0.05). Allometric scaling allowed us to rank participants’ performance across geometrically similar body sizes and underpinned the overall mechanical disadvantage of taller participants, as well as the role of the trunk-to-thigh body proportion in postural stability during squatting. Full article

Deciphering the dynamic fracture evolution of rock masses, particularly the interaction between dynamic stress waves and localised weak interlayers, is essential for optimising dynamic rock excavation in mining engineering. To systematically explore how these structural planes halt propagating cracks and generate a dynamic shielding effect, this study integrated Split Hopkinson Pressure Bar experiments, Digital Image Correlation techniques, and computational modeling. The findings demonstrate that altering the geometric orientation of the soft layer dictates the ultimate failure pattern. While an orthogonal interface (i.e., an interface with 0° inclination perpendicular to the loading direction) allows a tension-driven crack to cleave directly through the entire composite specimen, introducing an inclined obliquity of 15° forces the advancing fracture to deviate and permanently halt inside the soft stratum. Macroscopically, this barrier capability is validated by a rapid decrease in fracture speed, which drops abruptly by 75.5% upon encountering the inclined zone. Microscopic numerical evaluations confirm that this fracture arrest originates from wave mode conversion at the misaligned boundary. The angled interface forces incoming compressional pulses to transform into intense shear stresses, promoting extensive fracture. Substantial energy dissipation within the interlayer fully deprives the primary crack of the tensile stress required for propagation, effectively confining the stress-propagated hard rock within an energy shadow zone and suppressing further fragmentation. Full article

Background: Conventional Herbst appliances are effective for the correction of skeletal Class II malocclusion, but they are frequently associated with dentoalveolar side effects, particularly lower incisor proclination. Skeletal anchorage systems may improve orthopedic outcomes; however, submucosal miniplates require invasive surgical procedures that may reduce patient acceptance. This pilot clinical study evaluated the feasibility, safety, and skeletal effects of a minimally invasive digitally guided protocol using supragingival miniplates for bone-supported Herbst therapy in late adolescents. Methods: Eleven late-adolescent patients (14–17 years; cervical vertebral maturation stages CS4–CS5) with skeletal Class II malocclusion due to mandibular retrusion were prospectively treated using a bone-supported Herbst appliance anchored to digitally planned supragingival stainless-steel miniplates fixed with bicortical miniscrews. Miniscrew placement was planned by merging CBCT and intraoral scan data and performed using 3D-printed surgical guides. Cephalometric variables, including SNA, SNB, Wits appraisal, mandibular plane angle, and incisor inclinations, were assessed before treatment and after a 10-month Herbst phase. Mandibular advancement was additionally explored using a complementary linear measurement (SeMndb-line). Results: All patients completed treatment without anchorage loss, appliance failure, or surgical complications. Significant skeletal improvements were observed, including an increase in SNB (+3.36°, p < 0.001) and a reduction in Wits appraisal (−2.65 mm, p < 0.001). The SeMndb-line increased by +3.49 mm (p < 0.001), supporting effective mandibular advancement. Lower incisor inclination remained stable (Δ = −0.18°, p = 0.909), indicating effective dentoalveolar control. No clinically relevant changes in vertical skeletal pattern were observed. Conclusions: Digitally guided supragingival miniplates for bone-supported Herbst therapy appear to be a feasible and minimally invasive approach for the treatment of skeletal Class II malocclusion in late adolescents. This protocol achieved clinically meaningful mandibular advancement while minimizing dentoalveolar side effects. Given the pilot design, small sample size, and lack of a control group, further controlled studies with larger samples and long-term follow-up are required. Full article

Highly deviated wells commonly exhibit large errors in horizon calibration because the logging path follows an inclined borehole trajectory, whereas post-stack seismic processing effectively treats wave propagation as vertical. This mismatch has received limited attention. Here, we performed horizon calibration and velocity-model building for highly deviated wells drilled in the Mahu Sag, Junggar Basin, and obtained three key findings. First, the assumed vertical travel path in post-stack data is the primary cause of the initial mis-tie for highly deviated wells. Second, calibration in the deviated interval requires a strategy distinct from that of vertical wells and may involve substantial stretching or squeezing of the original logs to achieve a consistent time-depth relationship. Third, the map-view projection of a highly deviated well is essentially linear; relative to vertical wells, it provides denser in situ velocity constraints and, with pseudo-well control, supplies 2D velocity information along the well-trajectory plane, thereby improving velocity-field modeling. Validation against drilling data showed that this workflow improved well ties and refined the velocity model, providing practical guidance for geological well planning and reducing drilling risk. Full article

Composite ZnO/Fe nanostructured thin films are synthesized via physical vapor deposition using radio frequency magnetron sputtering in conventional, as well as in glancing angle deposition (GLAD) geometries. ZnO is employed as a compact nanocolumnar template to direct Fe growth in bilayer and multilayer architectures. Morphological analysis reveals well-defined ZnO/Fe interfaces for normal deposition geometry, with diminished interface clarity and reduced layer thickness in GLAD samples. Crystallographic characterization indicates clear ZnO-{002} and α-Fe-{110} texture. Magnetostatic characterization investigates the effects of morphology on coercivity and domain nucleation. GLAD-deposited Fe films exhibit clear in-plane magnetic anisotropy, with remanence to saturation magnetization (M_REM/M_SAT) equal to 1 for the easy axis and equal to 0.24 for the hard axis, consistent with inclined nanocolumn morphology. Our findings show that deposition geometry, rather the ZnO template, mostly affects the morphology of Fe films. The above, highlight the potential of engineered ZnO/Fe nanocomposites for magnetic, spintronic, and magnetoplasmonic applications, by tuning morphology and interface quality through deposition parameters. Full article

The Draa Sfar polymetallic mine, located near Marrakech in Morocco, represents the deepest currently operating underground mine in North Africa, with workings extending beyond depths of −1200 m. At such depths, mining activities are conducted within weak, highly anisotropic foliated black pelites, where recurrent instability mechanisms, most notably rib buckling and crown deterioration, are frequently observed, especially in drifts developed parallel to the foliation planes. In this context, the present study integrates detailed structural field observations with two-dimensional finite-element modelling using RS2 in order to analyse excavation-scale stability within these schistose pelitic rocks. Both numerical simulations and field evidence indicate that increasing depth-related confinement, together with a dominant in situ stress regime, favours stress channelling and localized damage development, while the pronounced transverse weakness of the pelites exerts a primary control on failure kinematics, including schistosity-parallel spalling, asymmetric rib buckling, and shear along inclined foliation intersecting the excavation back. Instability processes are further intensified by excavation geometry and mine layout: angular, square-shaped profiles and foliation-parallel drift orientations generate steeper stress gradients and greater convergence compared to arched sections, while proximity to stopes and adjacent openings enhances mining-induced stress redistribution and associated deformation. Intersection areas emerge as the most critical configurations, where the superposition of stress perturbations and structurally controlled damage mechanisms accelerates wall convergence and roof sagging. Overall, these findings demonstrate that drift stability cannot be adequately evaluated using generic design criteria when excavation geometry, interaction effects, and structural anisotropy exert a dominant influence on mechanical behaviour. Consequently, a fully integrated approach that combines drift geometry optimisation, detailed structural mapping, site-calibrated numerical modelling, and in situ monitoring is required to achieve reliable stability assessment and control. Full article

Background/Objectives: To Develop a CBCT-based transverse diagnostic method that establishes normative buccolingual inclination values for permanent first molars and objectively distinguishes between dentoalveolar transverse deficiency and skeletal maxillary deficiency. Methods: A total of 1120 initial CBCT scans were reviewed, and 40 subjects with normal occlusion met the inclusion criteria. Volumes were reoriented using a standardized three-plane protocol, and molar angulations were measured relative to reference planes parallel to the occlusal plane. Intra- and inter-examiner reliability were assessed using ICC. Descriptive, comparative, and correlation analyses were performed bilaterally and between arches. Results: No significant right–left differences were observed for upper molar angulation (URM vs. ULM: 99.5° vs. 99.1°; t(19) = 1.560, p = 0.135) or lower molar angulation (LRM vs. LLM: 78.9° vs. 78.9°; t(19) = 0.301, p = 0.767). Non-parametric analysis confirmed these findings (ULM vs. URM: Z = −1.203, p = 0.229; LLM vs. LRM: Z = −0.427, p = 0.669). Significant positive bilateral correlations were observed in both arches (upper: r_S = 0.784, p < 0.001; lower: r_S = 0.837, p < 0.001). A significant negative correlation was found between upper and lower molar angulations (left side: r_S = −0.626, p = 0.003; right side: r_S = −0.858, p < 0.001), demonstrating dentoalveolar compensation. Conclusions: CBCT enables the precise assessment of molar buccolingual inclination and the establishment of normative patterns essential for transverse diagnosis. The proposed method allows the quantification of the maxillary “basal defect” after virtual dental decompensation, providing an objective tool to differentiate dentoalveolar from skeletal transverse discrepancies and guide targeted treatment planning. Full article

Lower-limb rehabilitation exoskeletons must balance biomechanical compatibility, structural safety, and low mass to enable practical, repeatable gait assistance. This paper proposes a planar pantograph-derived exoskeleton leg driven by a Chebyshev Lambda linkage and develops an integrated workflow from mechanism synthesis to manufacturable optimization and experimental verification. A mannequin-coupled multibody model was built in MSC ADAMS to evaluate joint kinematics, end-point (foot) trajectories, and joint reaction forces under multiple scenarios (fixed-frame, ramp, stair ascent, and inclined-plane walking). The extracted joint loads were transferred to a parametric finite element model in ANSYS Workbench 2019, where response surface surrogates and a multi-objective genetic algorithm (MOGA) were used to minimize mass under stiffness and strength constraints. For the optimized load-bearing link, the selected minimum-mass design reached a component mass of 0.542 kg while respecting the imposed structural limits, i.e., a maximum total deformation below 0.2 mm and a maximum equivalent (von Mises) stress below 50 MPa (e.g., ~0.188 mm deformation and ~39 MPa stress in the optimal candidate). A rapid prototype was manufactured by 3D printing and experimentally evaluated using CONTEMPLAS high-speed video tracking, providing measured X_M(t) and Y_M(t) trajectories and joint-angle histories for quantitative comparison with simulations via RMSE metrics. Full article

Background and Objectives: Dentofacial asymmetries are common in patients with malocclusions, while mild body postural asymmetries are frequently reported in otherwise healthy individuals. However, their interrelationship remains insufficiently investigated in adults without diagnosed spinal disorders. This study aimed to evaluate the association between dentofacial and body postural asymmetries in adults with malocclusions. Materials and Methods: A clinical cross-sectional observational study was conducted on 102 adults (18–45 years) with malocclusions and no spinal pathology. Standardized clinical morphometric examinations assessed dentofacial asymmetries (horizontal and vertical planes), dental parameters (dental midlines deviation and occlusal plane inclination), and body postural asymmetries (head, shoulder, trunk, pelvic, and lower limb alignment). Asymmetries were recorded using predefined clinical thresholds. Statistical analyses included the Wilcoxon signed-rank test, Pearson chi-square test, and Spearman’s rank correlation coefficient. Results: Dentofacial asymmetries were identified in both planes and occurred more frequently on the left side. Horizontal facial asymmetries were most common at the cheek (74.5%), nostril (66.7%), and mandibular angle levels (57.9%), and were influenced by sex, age, facial growth pattern, and facial profile (p ≤ 0.05). Mandibular dental midline asymmetry was present in 55.8% of patients. Body postural asymmetries were also frequent, particularly unilateral (60.8%) or anterior (55.9%) head inclination and shoulder asymmetries (54.9%), with a predominance on the left side and associations with age, body mass index, and postural attitude (p ≤ 0.05). Correlations were identified among facial asymmetries and among body postural asymmetries (p ≤ 0.01), indicating a bilateral distribution pattern. Additionally, right-sided facial asymmetries showed significant positive associations with right-sided body postural asymmetries (ρ = 0.197–0.229; p ≤ 0.05). Conclusions: Dentofacial and body postural asymmetries have been identified in adults with malocclusions and presented side-specific associations regarding the patterns of asymmetry. Full article

The breakup of Intelsat 33E on 19 October 2024 posed a potential risk to satellites in the Geostationary Earth Orbit (GEO). This study analyzes the evolution and distribution of these fragments using a probabilistic approach. The initial distribution of the fragments, derived from the NASA Standard Breakup Model, indicates the generation of 4393 fragments larger than 1 cm. The spatial propagation of these fragments is modeled analytically in the Earth-Centered Earth-Fixed reference frame, showing the formation of high-density ring structures in the equatorial plane from 24 h to 28 days after the breakup. The orbits of 36 cataloged fragments are retrieved and compared with the probability density. Furthermore, Monte Carlo simulations validate the probabilistic model and highlight its efficiency in capturing low-probability events. Collision risks to other GEO satellites are assessed, showing that the top 10% of satellites encounter a collision probability of up to ${10}^{-8}$ after 28 days. Satellites near the equatorial plane are at higher risk, whereas those with higher inclinations are less affected. These findings underscore the need for enhanced monitoring and mitigation strategies for GEO breakup events, given the challenges in detecting small fragments. 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

The design of satellite constellations is a complex optimization problem interdependent with other decision problems and multiple competing, user-specific criteria. Consequently, it is very difficult to make a final decision on the constellation design. This study proposes a full simulation and evaluation framework for designing a satellite constellation. Firstly, constructing a solution space by constraining orbital parameters and varying satellite count and plane configuration. Secondly, employing six evaluation metrics—covering both cost and coverage—that are weighted via the case company, Sternula’s setting, with the TOPSIS approach for ranking the candidate constellations. A subsequent sensitivity analysis evaluates robustness to shifts in criterion weights and per-satellite cost. The study indicates that a Walker Star constellation with 97.5° inclination, 105 satellites in 15 planes (phasing 7) achieves the best cost–coverage balance for the case company and remains stable under weight and cost variations. Full article

We describe the formation of LIPSS by fs laser irradiation on polished titanium or steel samples, from which polymer replicas can be produced. The irradiation of inclined samples allows a variation in the periodicity of the LIPSS in a range between about 500 and 1000 nm, depending on the angle of incidence and the orientation of the laser polarization relative to the plane of incidence, either parallel (p-polarization) or perpendicular (s-polarization). For p-polarization, a second larger-size LIPSS feature with periodicities between about 1300 and 2200 nm is observed at medium angles. LIPSS lines are oriented perpendicular to the light polarization, except for s-polarization on steel samples, where a rotation of up to 35° is observed. In a two-step process, the LIPSS are replicated in polymers. We investigate the attachment of Schwann cells and fibroblasts seeded thereon, which show no direct dependence on the variation in the LIPSS periodicities. Full article

This study investigates the effects of an arch rib inclination angle and loading scenario on the elasto-plastic stability of steel basket-handle arches to support bridge design. A parametric finite element analysis was performed on 48 models, with inclination angles ranging from 0° to 15° under three vertical loading conditions: uniformly distributed (V), transversely eccentric (V₁), and longitudinally eccentric (V₂). A nonlinear analysis was conducted using the arc-length method. The results indicate that the ultimate bearing capacity is highest under loading V, followed by V₁ and V₂, irrespective of the inclination angle. The initial stiffness increases monotonically with inclination in all cases. Under V, the capacity peaks at a 10° inclination before declining, with a corresponding transition from out-of-plane to in-plane buckling at this critical angle. Under V₁, out-of-plane buckling dominates, and the capacity fluctuates slightly before increasing with the inclination. Under V₂, in-plane antisymmetric buckling prevails, and the capacity decreases gradually as the inclination increases. Eccentric loading induces severe stress concentration and local buckling at the arch feet, accelerating global failure. It is concluded that an inclination angle up to 10° enhances elasto-plastic stability under symmetric vertical loading, whereas eccentric loading substantially reduces the capacity; therefore, symmetric and simultaneous loading on both arches is recommended during construction. Full article

Rock-socketed piles have been widely adopted in engineering projects with complex geological conditions due to their high load-bearing capacity. However, the joints in rock masses significantly impact the lateral load-bearing performance of pile foundations. The inherent nonlinearity and heterogeneity of rock materials, combined with the limitations of field testing, make it challenging for existing calculation methods to accurately assess this influence. To address this issue, this study proposes a novel laboratory model testing method designed to simulate jointed rock masses and elucidate their impact mechanisms on the lateral load-bearing capacity of rock-socketed piles. First, through a combination of literature review and numerical analysis, we investigated the control parameters of the joint (spacing and inclination angle) on rock strength, identifying key input parameters in the Hoek–Brown criterion. Based on these findings, artificial rock samples were used to simulate real rock masses with different joint characteristics, and systematic lateral load-bearing model tests were conducted. Subsequently, the experimental results validated the refined numerical model, which was then applied for mechanism extension analysis. The results demonstrate that rock strength exhibits significant structural effects: strength peaks when joint planes are parallel to the direction of maximum principal stress, while it reaches its minimum when the angle between them is 30° to 45°. The lateral displacement at pile tops decreases with increasing joint spacing, while the initial stiffness of the load–displacement curve increases accordingly. The proposed experimental method provides a reliable technical approach for studying the lateral response of rock-socketed piles in jointed rock masses. These findings hold important theoretical value and engineering reference significance for enhancing understanding of the lateral load-bearing mechanisms of rock-socketed piles in jointed rock masses, as well as guiding their practical design and construction. Full article