Human spine development and ossification, from foetus to adolescent, is a complex, gradual process. Vertebra growth can be modulated by applying mechanical compression or distraction forces. Asymmetrical vertebra loading can thus create vertebral-body angular deformities and wedging. The aim of this study was to analyse vertebral body shapes on the latetal view of subjects with symptomatic lumbosacral transitional vertebrae (LSTV) and compare them to radiologically normal asymptomatic subjects. We compared skeletally mature adolescents with LSTV and sacralisation of L5 against asymptomatic controls. Spinopelvic parameters and vertebral wedging were compared for all lumbar vertebrae using their full-spine, sagittal plane, standing radiographs taken from 2015-2023. Multivariate logistic regression (adjusted for PI) was used to control for spinopelvic confounding, while intergroup differences in wedging and L1-S1 lordosis were assessed via two-tailed Student's t-tests. The LSTV group (n = 19, mean age 15.4 ± 1.4 years) exhibited significantly higher PI and L1-S1 lordosis (p < 0.01) than the control group (n = 17, mean age 14.7 ± 1.7 years), with comparable sex distribution in both cohorts. Univariate regressions showed that vertebral wedging angles were significantly higher among LSTV patients than controls at all vertebral levels. Multivariate regressions adjusted for PI found no statistical difference in L1-S1 lordosis between the two groups (p=0.872). However, L5 remained significantly more wedged (p=0.017) among LSTV patients. Findings suggested morphological adaptations at the transitional level, with higher L5 wedging angles among LSTV patients than among controls, independently of PI. LSTV acts as a posterior tether, modulating vertebral growth during development, potentially part of hyperextension mechanisms occurring above the transitional level to compensate for reduced mobility in the L5-S1 segment and hypoplastic discs. Longitudinal studies could help evaluate spinopelvic development over time among LSTV patients.

The effect of void distribution on yielding is investigated using periodic single-void tetragonal unit cells subjected to symmetric and asymmetric loading conditions. The behavior is compared to that of reference, cubic lattice and random dispersions across porosity levels spanning two orders of magnitude. Small-strain FFT-based simulations are performed using three-dimensional periodic cells with equiaxed voids embedded in an elastic–perfectly plastic matrix. Emphasis is placed on a regime termed unhomogeneous yielding, where deformation localizes into “layered” bands or columnar regions the orientation of which depends on void distribution as well as on the loading. A key feature is the percolation of nondeforming regions within the cell Consistent with the literature it is found that elongated tetragonal distributions consistently exhibit a softer response compared to both cubic and random distributions. On the other hand, flat cells are found to alter the mode of percolation. The extent of the apparent first-order effect of void distribution on yielding is analyzed in terms of the concept of band porosity. • Void distribution effects analyzed using an FFT method and tetragonal cells. • Effective yield surfaces predicted for two levels of porosity for ordered and random dispersions. • Uncovered distribution softening discussed in light of band porosity effects.

This study’s object is the stressed state of the plastic deformation site under conditions of load asymmetry when metal is gripped by rolls, under the determining modes of process stability. The task addressed is the implementation of shape change at the rolling process stability threshold related to a decreased force load under the increased strain impact. A physical and mathematical model of a flat rolling theory problem has been built under conditions of multi-parameter factors affecting the gripping capacity of rolls and the stability of rolling process. The plasticity theory problem was solved analytically using the method of argument of a function of a complex variable. The solution to the plane problem is shown, using the asymmetry of the process, the counter-directed flow of metal. The nonlinearity of the plasticity theory problem was taken into account. Based on the mathematical model, a new force factor was identified and investigated: the force stretching factor from the lagging zone. A new single-zone deformation mode with minimum process stability was identified. The process was investigated under conditions of multiparameter influence on rolls gripping ability and its stability. The zones of reachability were established for a deformation focus shape factor within the range of 5.00...15.00. The mode of partial suppression of the zeroing factors of the metal stressed state was investigated under conditions of multi-parameter influence on the gripping ability of the rolls and the stability of the process. Stability indicators of transient modes were determined: at α = 0.077, the ratio f/α = 1.10…1.95; at α = 0.129, the ratio f/α = 1.19…1.95; at α = 0.168, the ratio f/α = 1.28…1.95. This study’s results make it possible to solve technological problem related to the development of rolling schemes when the gripping force of friction and the pushing force of normal pressure arise during the forming process

Background: Low back pain (LBP) is a global health concern influenced by biomechanical factors, including lumbar alignment. Altered lumbar curvature (hyperlordosis/hypolordosis) may disrupt posture, plantar pressure distribution, and postural stability, contributing to LBP pathophysiology. Aim: This study investigated the impact of lumbar alignment on plantar pressure patterns and postural sway in individuals with LBP. Methods: Thirty-six participants (18–25 years) were categorized into hyperlordosis, hypolordosis, and normal lordosis groups. Lumbar curvature was measured using a flexible ruler, while plantar pressure and center of pressure (COP) parameters were assessed via the Zebris FDM-S platform during bipedal and unipedal standing. Statistical analysis included ANOVA and Tukey’s post hoc tests (SPSS v26, p&lt;0.05). Results: The normal lordosis group exhibited significantly smaller COP confidence ellipse parameters (minor/major axis length, area) and lower postural sway compared to hyperlordosis and hypolordosis groups (p&lt;0.05). Anterior-posterior plantar pressure asymmetry was pronounced in hyperlordosis (anterior shift) and hypolordosis (posterior shift). No significant differences were observed in mediolateral COP displacement or bilateral foot symmetry (p&gt;0.05). Conclusion: Normal lumbar alignment enhances postural stability and balanced plantar pressure distribution, whereas hyperlordosis and hypolordosis correlate with increased postural fluctuations and asymmetric foot loading. Rehabilitation strategies targeting lumbar alignment may improve biomechanical outcomes in LBP management.

To explore the application of precast concrete construction methods in underground stations, a combined precast and cast in situ construction method was adopted for a long-span column-free underground subway station. To study the stability of large-span underground arch structures under asymmetric loading, a full-scale test was conducted using the displacement-force control method. Steel blocks were used to simulate the overlying soil and additional loads on the upper surface of the arch, while the displacement of the arch foot was applied by adjusting the tension of the cables. The maximum tensile stress and maximum compressive stress of the steel bars appeared at the midpoints of the left and right arches, which were less than the yield stress of the steel bars. The results show that the structural stability meets the design requirements and provides a considerable safety margin. A comprehensive analysis of the arch structure under asymmetric loading was carried out through on-site monitoring, numerical simulation, and analytical solutions. The results are in good agreement: compared with the experimental results, the calculated values increase the maximum deflection of the arch by 13.67%, which verifies the reliability of the numerical simulation and analytical solution methods under the same boundary conditions. However, restricted by test conditions, the loading in this study was only applied on one side of the arch crown, which differs from the actual working condition involving full loading first followed by unloading on one side.

Fatigue damage of yawed wind turbine components can be caused by repeated long-term unsteady asymmetric inflow loads across the rotor swept area, necessitating fatigue load analysis to ensure the in-operation safety of wind turbines. This study investigates the impact of geometric nonlinearity on the fatigue loads of wind turbine components. The geometrically exact beam theory (GEBT), implemented in BeamDyn of OpenFAST, is employed to model full geometric nonlinearity. For comparison, ElastoDyn in OpenFAST, which uses the generalized Euler–Bernoulli beam theory for straight isotropic beams, is also utilized. Aeroelastic simulations were conducted for the national renewable energy laboratory (NREL 5 MW) and international energy agency (IEA) 15 MW wind turbines. Fatigue loads, quantified by the damage equivalent load (DEL) based on Palmgren–Miner’s rule, were analyzed for critical components, including blade out-of-plane (OOP) moments, low-speed shaft (LSS) torque, LSS bending moment (LSSBM), and tower base bending moment (TBBM). Results indicate that geometric nonlinearity significantly influences fatigue damage in critical turbine components, with significant differences observed between BeamDyn and ElastoDyn simulations.

To ensure the safety of twin tunnels in soil, especially closely spaced shield tunnels, it is critical to evaluate the adverse load on the preceding or existing tunnel induced by adjacent tunneling. This study proposes a novel arching effect designated as the ‘composite arching effect,’ characterized by positive and negative friction acting on opposite sides of the soil column above an existing tunnel. Based on Terzaghi’s theory and the double-trapdoor model, analytical solutions were derived to calculate the asymmetrical load on the preceding rigid tunnel (trapdoor) at shallow depths using the limit equilibrium method, accounting for the composite arching and load transfer induced by the following tunnel. Furthermore, an analytical solution for the load on the preceding flexible tunnel was presented when the two soil columns above the twin tunnels separated, reflecting the ground-lining interaction. The proposed method was validated through typical model tests of twin trapdoors and circular rigid tunnels. The theoretical analysis indicated that the vertical load on the preceding tunnel and the degree of load asymmetry increase with decreasing spacing and increasing shallow overburden depth, and the degree of load asymmetry increases with increasing internal friction angle and cohesion. The load on the preceding flexible tunnel increases rapidly with the ratio of the lining stiffness to the ground stiffness when the stiffness ratio is ≤0.2. In addition, a load mode for the preceding rigid tunnel at deep depths was proposed, and the load in the composite arching state is nearly independent of the deep overburden depth in good ground conditions. The interaction spacing between twin tunnels and the maximum spacing in composite arching increase significantly with increasing overburden depth but are less affected by the internal friction angle and cohesion.

Peak, cumulative and rate of medial and lateral compartment joint loading during gait following total knee arthroplasty.

Numerical analysis of dynamic response of UHPC beams under asymmetric impact loading

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Cavovarus foot deformity affects 8-15% of the population. Altered biomechanics place the ankle at increased risk for developing osteoarthritis (OA). Recent studies have leveraged weight bearing CT (WBCT) to better characterize joint biomechanics using computational modeling to analyze joint interactions during functional loading. The 3D models use discrete element analysis (DEA) to estimate joint contact stress. These techniques could assist in identifying patients at-risk of developing ankle OA secondary to cavovarus deformity. Various studies have indicated a link between morphologic changes of the tibiotalar joint and the development of ankle OA. We hypothesize that anatomic positioning of the ankle joint is associated with increased asymmetric loading in the setting of cavovarus hindfoot alignment. Chronic increases in contact stress would increase the risk of ankle OA. Methods: We studied WBCT scans of three patient cohorts: healthy controls with no underlying ankle deformity (39 feet), patients with idiopathic cavovarus (24 feet), and patients diagnosed with cavovarus deformity from Charcot-Marie-Tooth disease (22 feet). WBCT scans were segmented using DISIOR/Paragon28 to generate 3D surface models of the loaded tibia and talus. These models were aligned and smoothed using Geomagic Design X. Opposing cartilage surfaces were then imported into MATLAB for analysis using previously developed DEA code which treats subchondral bone as a rigid body and articular cartilage as an isotropic linear elastic material, idealized as a bed of springs. DEA was performed over 13 loading instances from the gait cycle with boundary conditions consistent with anatomic loading. Contact stress overexposure (CSTE) was analyzed using previously established methods (Figure 1). Statistical differences between each group were analyzed using two-tailed Wilcoxon rank-sum tests with a significance level of 0.05 (p &lt; 0.05). Results: Significant differences were observed between the control group and idiopathic group for both the area over the damage threshold (0.87 mm2 vs 17mm2, p &lt; 0.0001) and the maximum contact stress overexposure (4.17 MPa•s vs 7.08 MPa•s, p &lt; 0.0001). Significant differences were also observed between the control group and the CMT disease group for both the area over the damage threshold (0.87 mm2 vs 7.39mm2, p = 0.01) and the maximum contact stress overexposure (4.17 MPa•s vs 5.53 MPa•s, p = 0.007). Conclusion: We hope that the development of this model will enable patient-specific prediction of progression to ankle arthritis, leading to subsequent identification, arthritic degeneration prevention, and management of at-risk patients. Figure 1: Representative Patient Contact Stress Time Exposure Maps

We describe the mathematical modeling of the lumbar spine with reduced bone min-eral density using the finite element method (FEM). The main focus is based on the com-parison of the biomechanical characteristics of two stabilization systems: rigid interlami-nar stabilization (RIS) and transpedicular fixation (TPF). Methods: The study was per-formed by mathematical modeling using the finite element method (FEM) to assess the distribution of stresses and deformations during transpedicular fixation (TPF) and rigid interlaminar stabilization (RIS). The data were compared to computer tomography of pa-tients, anatomical features of vertebras and characteristics of bone tissue. The biome-chanical effects of stabilization systems were evaluated under various types of loads cor-responding to physiological conditions: axial load: imitation of vertical load in a stand-ing position (50 kgf). Flexion and extension: modeling the flexion and extension of the spine. Lateral inclinations: lateral inclinations taking into account the asymmetric load on the intervertebral discs and ligaments. Twisting: rotational loads with assessment of im-plant stability. Results: It was revealed that transpedicular fixation is accompanied by increased loads on adjacent vertebrae, which increases the risk of adjacent segment syndrome. Rigid interlaminar stabilization allows more adequate distribution of loads, but increases stress in the arches of the vertebrae. Our data are consistent with the results of studies, confirming the need for an individual approach to the choice of a stabilization method in patients with osteoporosis. Conclusions Rigid interlaminar stabilization is preferred for patients with osteoporosis, while transpedicular fixation remains the stand-ard for severe instability.

Actuating monolithic photonic components (particularly slab waveguides) requires higher force due to their inherent stiffness. However, two primary constraints must be addressed: actuator footprint and fabrication limits. Increasing the number of fingers to provide the required force is not a viable solution due to space constraints, and we must also adhere to the process design kits of standard fabrications and respect their design limits. Therefore, it is crucial to increase the actuator force output without significantly enlarging the actuator footprint while maintaining the necessary travel range. In order to achieve this, we utilize arrays of electrostatic comb drives, with each repeating cell geometry optimized to produce the highest force per actuator footprint. Our optimization strategy focuses on finger geometry, the arrangement of fingers and arms design in the comb structure, including the number of fingers per arm and arm length, ensuring that each repeating cell delivers maximum force per unit area or force intensity. Co-optimizing a repeatable, footprint-optimized comb-array unit cell (arm length, arm width, finger pitch, finger count) and validating it against an asymmetric slab waveguide load, we reach a maximum pre-pull-in force intensity of about 342 N m−2 at 70 V with about 6 µm travel, confirmed by analytical modeling, numerical simulation, and measurement. Despite fabrication challenges such as over-etching and variations in electrode dimensions, detailed SEM analyses and correction functions ensure that the theoretical models closely match the experimental data, confirming the robustness and accuracy of the design. These optimized actuators, capable of achieving substantial force output without sacrificing travel range or mechanical stability, are particularly effective for applications in optical beam steering for in-plane silicon-photonics and related optical microsystems applications.

Knee injuries are highly prevalent in fencing, as the sports rapid directional changes, explosive lunges, and asymmetric lower-limb loading frequently cause issues like anterior cruciate ligament (ACL) tears and patellar tendon strain, which threaten athletes performance and long-term career sustainability. Addressing these injuries with effective rehabilitation is crucial for safeguarding fencers athletic careers. This paper focuses on a fencing-specific rehabilitation framework for knee injuries and compares its outcomes against general orthopedic protocols and the FIFA 11+ protocol. The fencing-specific framework is divided into four progressive phases: acute protection, strength restoration, dynamic stability, and return-to-sport reconditioning. Integration of sport-specific biomechanics, psychological readiness assessment, and data-driven monitoring into this framework yielded superior rehabilitation outcomes. Compared to general and FIFA 11+ protocols, the fencing-tailored approach shortened recovery time, enhanced neuromuscular control, and better restored athletes competitive readiness. These findings emphasize the necessity of designing rehabilitation protocols based on fencings unique demands, providing a practical model for clinicians, coaches, and sports organizations to improve fencers health and maintain their competitive performance.

Individual Pitch Control (IPC) is a crucial mechanism for mitigating asymmetric loads in offshore floating wind turbines (OFWTs). Conventional IPC systems face significant limitations in wind speed estimation accuracy and control strategy robustness, leading to load fluctuations and power degradation. To address these challenges, this study proposes a novel IPC system incorporating an innovative effective wind speed estimation method and a fuzzy PID control strategy. The wind speed estimation is achieved using polynomial fitting of the tip speed ratio and pitch angle. The fuzzy PID control strategy for IPC employs variable control gains calculated based on wind speed, azimuth angle, and blade root loads. To verify the performance of the proposed control system, it is compared against the baseline control system implemented in the OpenFAST software v1.0.0 by a case study of the NREL 5MW OFWT. Results demonstrate that the proposed system has high accuracy in wind speed estimation and maintains rated power output while reducing blade flapwise and pitching moments. Notably, the proposed EWSE has a 53.1% improvement in median error and a 19.23% improvement in data error threshold compared with a reference EWSE. Under strong turbulent conditions (15% turbulence intensity), the proposed system achieves a reduction of 17.9% in flapwise moment and 12.9% in pitching moment compared with a baseline controller.

Shear strength and shear energy measurement of brittle materials using two novel disc and beam shape configurations under asymmetrical three-point bend loading

Doubly fed induction generators have become widespread in generation systems in which maintaining the rotor speed cannot be fully performed by adjusting the drive mechanism. Purpose. Establishing instantaneous power of a doubly fed induction generator in an autonomous system with a nonlinear load under the condition of changing the machine stator windings’ electrical parameters. Methodology. As a result, of the known studies analysis, the presence of technical solutions that provide control of the generator rotor current even under conditions of nonlinear or asymmetric load was established. Using the known provisions of the electrical engineering theory and the electric machines theory using the instantaneous power balance principles, the balance equations for a three-phase double feed induction generator were determined. Findings. A model was synthesized for studying the processes of power components distribution of the equivalent circuit elements of a doubly fed induction generator in a visual programming package. The specified model allows simulating the modes of the machine with linear and nonlinear generator loading and asymmetry of the stator windings’ electrical parameters. Under the conditions of conducting experiments, a significant change was noted in the electromagnetic power spectrum of a phase rotor windings under conditions of asymmetry, which is characterized by the presence of power harmonics with a 50 Hz frequency, which corresponds to the interaction of the rotor phases’ direct current with the alternating voltage components of the rotor circuit’s corresponding element. Originality. During the study under the condition of asymmetry of the stator windings’ electrical parameters, it was established that the electromagnetic power harmonics of the stator windings’ phases have values that exceed the nominal power of the machine by a magnitude order and, being formed into the total power of the three phases, mutually compensate each other. Moreover, the level of these harmonics is sensitive to the nature of the asymmetry at a frequency of 100 Hz. In the power of three phases of elements of a doubly fed induction generator under the experiment conditions, constant components dominate, the level of which for the stator circuit is sensitive to the nature of the electrical parameters’ asymmetry of the stator windings and leads to changes by more than 2.3 % for the stator windings electromagnetic power and 2.2 % for the mechanical power. Practical value. The obtained results can be used in the future to improve the systems for the mode parameters control of a doubly fed induction generator to energy performance increase of the complex.

This paper presents an original approach through Transfer-Matrix Method applied for the calculus of the continuous circular plate embedded at the exterior circumference, charged with asymmetrical uniform load on the entire upper surface of the plate. Continuous circular plates are elements often found in practice, in the machine building, aeronautics, chemical industries (the bottoms of chemical reactors), and in petrochemical, mechanical, robotic, medical, military, nuclear, and aerospace industries. The calculus of continuous circular plates is a special problem both from the point of view of the theory of elasticity and from the point of view of the mathematical approach. The results obtained with Transfer-Matrix Method were compared and validated with those obtained from classical analytical calculation, the Theory of Elasticity. Transfer-Matrix Method is an elegant method and relatively easy to program. In future research, we want to validate our results with those given by the Finite Elements Method and those measured experimentally.

The study presents an analysis of steel-Ultra-High Performance Concrete (UHPC) composite girders. Five composite girder specimens were designed and tested. Analytical strain solutions for the composite girders under asymmetric axial loading were derived using the energy variation method. Results indicate that asymmetric axial forces significantly exacerbate the shear lag effect. Decreasing the width-to-span ratio reduces the shear lag coefficient, while reducing the width-to-depth ratio increases it. The parametric analysis indicates that, under asymmetric axial loading, increasing the strength of the concrete is an effective method to reduce the shear lag effect of the composite girders. Increasing the thickness of the UHPC slab proves to be effective in reducing the shear lag effect. Furthermore, the study indicates that when the b2/b1 ratio is less than 1, it has a tiny impact on the shear lag effect; however, when the b2/b1 ratio is greater than 1, the shear lag effect becomes more pronounced with increasing b2/b1. Additionally, the thickness of the flange plate and web plate of the steel girder has no significant effect on the shear lag effect. The results of the analysis can provide references for similar designs and constructions of composite structures.

Research on monitoring stress and deflection under asymmetric loading during bridge construction based on machine vision technology

Limited evidence exists on how segmental external load is distributed during linear running and how it varies with speed, training intensity, and individual differences. This study examines the external load profile across six body segments in elite female futsal players during linear treadmill running, focusing on the effects of speed and training zone, as well as individual variability. Eight elite players, including six outfield players and two goalkeepers (mean age 23.9 ± 3.4 years, height 164.96 ± 4.22 cm, body mass 60.31 ± 4.56 kg), performed an incremental test and were measured using six WIMU PRO™ inertial sensors. The sensors recorded segmental PlayerLoad, speed, and training zones. Data were analyzed using Linear Mixed Models. The most important results show significant interactions between body location and speed and between body location and training zone (p < 0.001), with intraclass correlation coefficients (ICC) ranging from 0.437 to 0.515. These results indicate variability among players and specific and asymmetrical segmental load patterns. These findings offer practical insights for tailoring individualized training strategies that optimize performance and reduce segment specific overuse injuries.