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Simplified loading conditions such as pure moments are frequently used to compare different instrumentation techniques to treat spine disorders. The purpose of this study was to determine if the use of realistic loading conditions such as muscle forces can alter the stresses in the implants with respect to pure moment loading. A musculoskeletal model and a finite element model sharing the same anatomy were built and validated against in vitro data, and coupled in order to drive the finite element model with muscle forces calculated by the musculoskeletal one for a prescribed motion. Intact conditions as well as a L1-L5 posterior fixation with pedicle screws and rods were simulated in flexion-extension and lateral bending. The hardware stresses calculated with the finite element model with instrumentation under simplified and realistic loading conditions were compared. The ROM under simplified loading conditions showed good agreement with in vitro data. As expected, the ROMs between the two types of loading conditions showed relatively small differences. Realistic loading conditions increased the stresses in the pedicle screws and in the posterior rods with respect to simplified loading conditions; an increase of hardware stresses up to 40 MPa in extension for the posterior rods and 57 MPa in flexion for the pedicle screws were observed with respect to simplified loading conditions. This conclusion can be critical for the literature since it means that previous models which used pure moments may have underestimated the stresses in the implants in flexion-extension and in lateral bending.

The infrastructures that were constructed decades ago do not meet the present structural benchmark, and they need to be demolished. In order to reclaim these lands, the existing pile foundations must be removed; otherwise, the land will lose its value. Since the piles are pulled out, vacant spaces are created in the ground. This causes the surrounding ground to experience settlement, jeopardizing its stability. The degree of influence depends upon the number of boreholes, the saturated condition of the ground, the time period of the vacant condition, the presence of loading, etc. It is important to understand the scope of the probable settlement under various situations. This study focused on determining the amount of displacement and its range for three different saturated soil types under loaded and unloaded conditions using the finite element method (FEM) analysis. It was observed that stiff ground underwent maximum deformation, while soft ground experienced the maximum influence from external factors. Moreover, the presence of loading not only increased the displacement amount and range, but it also caused a change in the location of the maximum displacement.

The application of plug-in electric vehicles (PEVs) is assumed to be wide in power system in regulating the system frequency in the near future. This paper provides an aggregate model of an interconnected multi-area thermal system with the incorporation of PEVs for frequency control in each of the three areas. Two degree of freedom proportional–integral–derivative (2DOF-PID) controller has been utilised for robust secondary control in all the three control areas. An optimisation technique inspired by nature named as wind-driven optimisation (WDO) technique is employed to decide the optimal values of the controller gains. The effectiveness of WDO optimised 2DOF-PID controller is verified by performing various comparative analysis with conventional PID controller under nominal system condition and random loading condition. An analysis has also been carried out to evaluate the system performance with variation in state of the integrated PEVs. The impact of introducing PEVs in the system in frequency regulation has been vigorously studied under different system conditions such as nominal, random loading condition, and simultaneous perturbation in two and three areas to testify their advantages. The comparisons reveal that with the integration of PEVs in the system, the system dynamics gets enhanced to a large extent.

Although silicon is the preferred choice for microelectromechanical systems (MEMS) piezoresistive pressure sensors, such devices are not preferred for application in harsh environmental conditions due to the exponential increase in leakage current with temperature. To alleviate such shortcomings of silicon-based pressure sensors in extreme conditions including elevated temperature and intense vibration, this study strives to shift focus from core complementary metal–oxide–semiconductor (CMOS) materials to silicon carbide. In this work, we adopt an analytical and simulation approach to model and analyze various characteristics of such silicon carbide piezoresistive sensors and determine an optimal design. A square diaphragm is modeled using the analytical expressions for a thin plate in combination with small-deflection theory, providing quick insight for estimation of critical parameters and thus the behavior of the pressure sensor. Both clamped and freely supported edge conditions of the diaphragm are explored. Although many studies and discussions are available on the rigidly supported loading condition, the freely supported edge condition for a square diaphragm has received little attention. The deflection, stress, strain, and sensitivity of the square diaphragm under both loading conditions are reported herein then compared to understand which of the two loading conditions results in more significant outputs.

Combined knowledge of the functional kinematics and kinetics of the human body is critical for understanding a wide range of biomechanical processes including musculoskeletal adaptation, injury mechanics, and orthopaedic treatment outcome, but also for validation of musculoskeletal models. Until now, however, no datasets that include internal loading conditions (kinetics), synchronized with advanced kinematic analyses in multiple subjects have been available. Our goal was to provide such datasets and thereby foster a new understanding of how in vivo knee joint movement and contact forces are interlinked – and thereby impact biomechanical interpretation of any new knee replacement design. In this collaborative study, we have created unique kinematic and kinetic datasets of the lower limb musculoskeletal system for worldwide dissemination by assessing a unique cohort of 6 subjects with instrumented knee implants (Charité – Universitätsmedizin Berlin) synchronized with a moving fluoroscope (ETH Zürich) and other measurement techniques (including whole body kinematics, ground reaction forces, video data, and electromyography data) for multiple complete cycles of 5 activities of daily living. Maximal tibio-femoral joint contact forces during walking (mean peak 2.74 BW), sit-to-stand (2.73 BW), stand-to-sit (2.57 BW), squats (2.64 BW), stair descent (3.38 BW), and ramp descent (3.39 BW) were observed. Internal rotation of the tibia ranged from 3° external to 9.3° internal. The greatest range of anterio-posterior translation was measured during stair descent (medial 9.3 ± 1.0 mm, lateral 7.5 ± 1.6 mm), and the lowest during stand-to-sit (medial 4.5 ± 1.1 mm, lateral 3.7 ± 1.4 mm). The complete and comprehensive datasets will soon be made available online for public use in biomechanical and orthopaedic research and development.

The critical clinical and scientific insights achieved through knowledge of in vivo musculoskeletal soft tissue strains has motivated the development of relevant measurement techniques. This review provides a comprehensive summary of the key findings, limitations, and clinical impacts of these techniques to quantify musculoskeletal soft tissue strains during dynamic movements. Current technologies generally leverage three techniques to quantify in vivo strain patterns, including implantable strain sensors, virtual fibre elongation, and ultrasound. (1) Implantable strain sensors enable direct measurements of tissue strains with high accuracy and minimal artefact, but are highly invasive and current designs are not clinically viable. (2) The virtual fibre elongation method tracks the relative displacement of tissue attachments to measure strains in both deep and superficial tissues. However, the associated imaging techniques often require exposure to radiation, limit the activities that can be performed, and only quantify bone-to-bone tissue strains. (3) Ultrasound methods enable safe and non-invasive imaging of soft tissue deformation. However, ultrasound can only image superficial tissues, and measurements are confounded by out-of-plane tissue motion. Finally, all in vivo strain measurement methods are limited in their ability to establish the slack length of musculoskeletal soft tissue structures. Despite the many challenges and limitations of these measurement techniques, knowledge of in vivo soft tissue strain has led to improved clinical treatments for many musculoskeletal pathologies including anterior cruciate ligament reconstruction, Achilles tendon repair, and total knee replacement. This review provides a comprehensive understanding of these measurement techniques and identifies the key features of in vivo strain measurement that can facilitate innovative personalized sports medicine treatment.

The protolith of the hanging wall and footwall of a fault plays a crucial role in influencing the sliding stability of the fault, and different protoliths have different tendencies toward sliding instability. To investigate the influence of protoliths on fault sliding stability, simulated fault friction sliding tests were conducted on five types of rocks: fine sandstone, limestone, marble, basalt, and granite, under various loading conditions. The test results demonstrate that, under the same loading conditions, basalt and granite exhibit a greater inclination toward unstable sliding during fault simulation, primarily displaying regular stick–slip and regular inclusion chaotic stick–slip behaviors. On the other hand, fine sandstone, limestone, and marble are predominantly characterized by stable sliding behaviors. The order of sensitivity for the influencing factors on sliding mode is the type of protolith, followed by initial normal stress, and then displacement loading rate. Based on the type of protolith and loading conditions (initial normal stress and displacement loading rate), the sliding mode can change during the sliding process of the simulated rock faults, transitioning from stable sliding to chaotic stick–slip, and then to regular stick–slip. Alternatively, the sliding mode can shift from regular inclusion chaotic stick–slip to regular stick–slip, or from regular stick–slip to stable sliding. Finally, the complexity of sliding patterns in different types of protoliths is analyzed from the perspectives of mineral composition and microstructure, elucidating the underlying mechanisms behind three sliding patterns: stable sliding, chaotic stick–slip, and regular stick–slip. Furthermore, the degree to which different types of rocks tend toward stick–slip behavior can be ranked as follows: rock mineral composition, mineral particle size, and structure among rock minerals. These research findings contribute to a deeper understanding of fault sliding behavior.HighlightsExperimental studies have shed light on the influence of protolith type on the stability of fault sliding, revealing that different rock types exhibit a preference for stick–slip behavior in the following descending order: rock mineral composition, mineral grain size, and structure among rock minerals.Further investigations have identified that basalt and granite tend to display unstable sliding, whereas fine sandstone, limestone, and marble are predominantly characterized by stable sliding. Intriguingly, a novel fault sliding mode named regular inclusion chaotic stick–slip has been uncovered.By delving into the mineral composition and microstructure, a comprehensive understanding of the underlying causes for the intricate variations in sliding modes across different protolith types has been attained.

Steel Shear Walls (SSWs) are known as structures that dampen the seismic loads like earthquakes in every construction, especially in tall buildings. The SSW contains three critical elements; beam, column, and infill plate. These elements have a significant effect on the seismic performance of the SSWs. The infill plate of SSW is important due to the absorption of the induced external energies. The current research paper studied different configurations of the sandwich panels with trapezoidal corrugated cores as the stiffeners inside the infill plate of the SSWs numerically in the presence of cyclic loading conditions. Two directions the horizontal and vertical are considered for the stiffeners. Also, various numbers of rows and columns are assumed for the stiffeners. The initial model was validated with the published experimental data. According to the average values that obtained, the horizontally and vertically oriented sandwich panels increase the plastic dissipation energy of the SSWs by around 156% and 196%, respectively. The outputs derived from this study will help to increase the SSWs’ strength in the built constructions by using sandwich panels inside them. Because the sandwich panels have low weight and high strength compared to the other stiffening systems.

Coral aggregate concrete (CAC) is a promising sustainable material for construction on remote islands, but it is often limited by relatively low strength and durability. Fiber reinforcement has therefore been introduced as an effective modification strategy. This review focuses on fiber-reinforced coral aggregate concrete (FRCAC), highlighting the roles of different synthetic and natural fibers in improving its performance. Firstly, the characteristics of coral aggregates and the effects of seawater mixing are summarized. Then, the influence of fiber incorporation on the mechanical behavior of CAC under static loading, including compressive, tensile, and flexural responses, is reviewed. In addition, the performance of FRCAC under dynamic and complex loading conditions, such as impact, cyclic, and triaxial loading, is discussed. Overall, fiber reinforcement significantly enhances the tensile strength, ductility, and energy dissipation capacity of CAC, particularly at high strain rates. The maximum reported improvements in splitting tensile strength and flexural strength can reach up to approximately 58% and 68%, respectively, depending on fiber type and dosage. However, the enhancements in compressive strength and elastic modulus are generally limited, with maximum reported increases of about 23% and 7%, respectively. Under multiaxial stress states, fibers mainly contribute to crack control and damage mitigation rather than substantial strength enhancement. Durability and environmental aspects are also addressed. Fiber addition may reduce chloride ingress in CAC, although long-term durability data remain limited. The use of coral aggregate must be balanced with the need to protect coral reefs. Finally, key knowledge gaps and future research directions are identified to support the sustainable application of FRCAC in marine infrastructure.

Background The onset and progression of osteoarthritis, but also the wear and loosening of the components of an artificial joint, are commonly associated with mechanical overloading of the structures. Knowledge of the mechanical forces acting at the joints, together with an understanding of the key factors that can alter them, are critical to develop effective treatments for restoring joint function. While static anatomy is usually the clinical focus, less is known about the impact of dynamic factors, such as individual muscle recruitment, on joint contact forces. Methods In this study, instrumented knee implants provided accurate in vivo tibio-femoral contact forces in a unique cohort of 9 patients, which were used as input for subject specific musculoskeletal models, to quantify the individual muscle forces during walking and stair negotiation. Results Even between patients with a very similar self-selected gait speed, the total tibio-femoral peak forces varied 1.7-fold, but had only weak correlation with static alignment (varus/valgus). In some patients, muscle co-contraction of quadriceps and gastrocnemii during walking added up to 1 bodyweight (~ 50%) to the peak tibio-femoral contact force during late stance. The greatest impact of co-contraction was observed in the late stance phase of stair ascent, with an increase of the peak tibio-femoral contact force by up to 1.7 bodyweight (66%). Conclusions Treatment of diseased and failed joints should therefore not only be restricted to anatomical reconstruction of static limb axes alignment. The dynamic activation of muscles, as a key modifier of lower limb biomechanics, should also be taken into account and thus also represents a promising target for restoring function, patient mobility, and preventing future joint failure. Trial registration German Clinical Trials Register: ID: DRKS00000606 , date: 05.11.2010.