Search Results (454)

The paper presents four solutions to the voltage source inverter (VSI) control system with existing delays in the measurement channels and the middle switching frequency (25,600 Hz): Single-Input Single-Output Coefficient Diagram Method (SISO-CDM), Multi-Input Multi-Output Passivity-Based Control (MISO-PBC), Multi-Input Multi-Output One-Sample-Ahead Preview Controller (MISO-OSAP), and MISO-OSAP with Luenberger Observer (MISO-OSAP-LO). The theory, including adjustments to controller gains or to the coefficients of the characteristic equation of the closed-loop system, is presented. Simulations of the VSI operation with these control systems for the nonlinear load and the dynamic resistive load (per the requirements of the EN 62040-3 standard) are presented. The SISO-CDM and MISO-PBC are finally selected for experimental verification of the simulations. The results of the tests enable the selection of the control type for a particular VSI design based on its cost and an estimation of the advantages of the more expensive solution. The paper should help in engineering design according to the remarks in the paper. Full article

Flexible interconnection systems (FISs) improve distribution flexibility, yet they remain vulnerable to pronounced nonlinear instability and potentially severe DC-link voltage collapse during large disturbances such as constant power load (CPL) surges. Conventional linear control methods are often unable to prevent deep transient voltage dips under these conditions. To address this issue, this paper proposes a novel large-signal stability criterion based on mixed potential function (MPF) theory. Unlike conventional Lyapunov-based approaches, the proposed formulation explicitly incorporates the dynamics of the DC capacitor, thereby enabling the derivation of a closed-form stability boundary. On this basis, the proportional gains of the outer voltage loop are first optimized to guarantee an adequate static stability margin. Subsequently, a power differentiation feedforward control strategy is developed. Rather than passively counteracting transients, the proposed method dynamically adjusts the DC voltage reference according to the rate of change in power, thereby actively reshaping the transient trajectory. In this way, the simple PI control framework is preserved while avoiding the heavy computational burden associated with advanced methods such as model predictive control. Simulation results show that the proposed strategy increases the permissible CPL step power by 8.7%, from 92 kW to 100 kW. Moreover, under severe load surges and weak grid conditions, the method prevents voltage collapse and maintains the transient trajectory above the practical 600 V safe-operation threshold. This computationally efficient strategy significantly improves the robustness and continuity of operation of practical FISs. Full article

Friction dampers are widely used as passive energy dissipation devices in seismic protection systems; however, their response depends on numerous interacting parameters, complicating design. This study focuses on the CAR1 friction damper, investigating parameter influence and enabling efficient inverse identification of those that meet prescribed performance objectives. A finite element (FE) model reproduces the nonlinear damper behavior under seismic loading validated by previous experimental results. Based on the finite element (FE) dataset, an artificial neural network (ANN) is developed as a surrogate model to approximate the system response. This approach aims to overcome the excessive computational cost of the finite element method when performing optimization tasks involving numerous model evaluations. Global sensitivity analysis using the FAST and Sobol indices quantifies the influence of the parameters, revealing that a subset governs most of the variability for the target control axial force and dissipated energy. Building on these results, an inverse ANN has been contacted to optimize the parameters of the device based on (i) target control axial force, and (ii) maximum dissipated energy to a target displacement, providing a practical, physically informed tool for tailoring CAR1 friction dampers to specific seismic objectives. Full article

Background: During aging, skeletal muscle mass constantly diminishes and myogenic potential declines. At the cellular level, a decline in mitochondrial function is a hallmark of the aging process and the deficiency of the mitochondrial network contributes to a progressive reduction in muscle mass. Autophagic clearance of mitochondria through the process of mitophagy is required to remove impaired or damaged mitochondria, while mitophagy is a key regulator of muscle maintenance. Dysfunctional degradation of mitochondria is increasingly associated with aging (mitophaging), while mechanical stimuli have been shown to ameliorate the aging-induced impaired muscle mass and function; however, less is known about the potential effects of mechanical loading on mitophaging. The aim of the present study was to investigate the effect of mechanical stretching on mitophagy in aged myoblasts, in vitro. Methods: Cell senescence was replicated using a multiple cell division model of C2C12 myoblasts. The control and aged cells were cultured on elastic membranes and underwent passive stretching using a mechanical loading protocol of 15% elongation for 12 h at a frequency of 1 Hz. Cell signaling and gene expression responses of mitophagy-associated and myogenic regulatory factors (MRFs) were assessed through immunoblotting and qRT-PCR of the cell lysates derived from stretched and non-stretched control and aged myoblasts. Results: Mitophagy factor AMP-activated protein kinase (AMPK), mitochondrial biogenesis stimulator peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1a), and mitophagy/mitochondrial biogenesis factor Parkin were downregulated in control stretched myoblasts compared to non-stretched cells, while the specific mechanical loading protocol used also reduced the phosphorylation of unc-51-like autophagy-activating kinase 1 (p-ULK1) (p < 0.05), as well as the expression of myogenic factor 5 (Myf5) and myogenic factor 4 (myogenin) (p < 0.001). Interestingly, this mechanical loading resulted in increased PGC-1a and Parkin expression (p < 0.05) and induced the previously undetected BCL2 interacting protein 3-like (BNIP3L/NIX) and AMPK expression and p-ULK1 activation in the aged myoblasts. In addition, mechanical stretching differentially affected the expression of MRFs in aged cells, upregulating the early differentiation factor, Myf5 (p < 0.01), while downregulating the late differentiation factor myogenin (p < 0.001). Conclusions: These findings suggest the beneficial effects of mechanical loading on the impaired mitophagy and early differentiation in aged myoblasts, as indicated by the mitophagy initiation and the promotion of mitochondrial biogenesis in these cells. The mechanical loading-induced downregulation of mitophagy and myogenesis in the control myoblasts might indicate their loading-specific differential responses compared to the aged cells. Full article

Age-related declines in balance and cognitive function increase fall risk and reduce quality of life in older adults and people with neurological disorders. Studying these changes in unimpaired adults provides a normative reference for identifying pathological deviations. However, most dual-task studies focus on single cognitive tasks and static conditions, specifically during gait, limiting understanding of how cognitive demand interacts with postural control while standing and during dynamic challenges. This study identified cognitive and motor outcomes most sensitive to age-related differences during motor–cognitive dual tasks of varying complexity across static and dynamic balance conditions, accounting for minimal detectable change. Sixty healthy adults performed dual-tasks ranging from simple motor activities to complex cognitive challenges (Stroop Test) while standing on a robotic platform. Cognitive performance (reaction time) and balance outcomes, including trunk and center of pressure (CoP) sway area, were assessed. Reaction time was sensitive to aging, with standardized estimates ranging from 0.014 to 0.036. The highest values occurred in the most demanding dual-task condition, enabling detection of meaningful change over short timeframes. Age effects on balance were modest under static conditions but amplified during dynamic perturbations across all dual tasks. In the SCWT 3 condition, standardized estimates for CoP sway area increased from 0.006 in the static condition to 0.047 in the passive condition, reflecting an approximately eightfold increase in age sensitivity. Trunk sway primarily reflected cognitive load, whereas CoP sway was most sensitive to balance perturbations and exceeded minimal detectable thresholds over only a couple of years. These findings support sensitive task–condition combinations for early detection and monitoring of age-related cognitive and balance decline. Full article

The earthquake doublet on 6 February 2023 served as an important test in Türkiye. It helped assess the vulnerability of Türkiye’s building stock under different seismic loading conditions across a large region. The widespread destruction and casualties observed in heavily damaged cities following the 6 February 2023 earthquakes served as a warning. This urged a re-evaluation of the seismic performance assessment framework and risk mitigation strategies. Seismic isolation technology is considered the best method for earthquake-resilient design. Passive control systems are primarily preferred for use in critical facilities, such as healthcare complexes and data centers. Properly designed seismically isolated hospital buildings exhibited superior performance during the 6 February 2023 earthquakes compared to fixed-base counterparts. However, their use in residential buildings in Türkiye is still limited due to impediments such as stringent code requirements and peer review processes. This study evaluates the effectiveness of the ELF procedure in the Turkish Seismic Design Code-2018, incorporating two site-specific studies and earthquake record scaling in Antakya city center. Moreover, it examines the influence of considering directivity effects for using seismic isolation systems in regions with high seismicity. An effective and rapid evaluation procedure is employed for the inelastic response of seismically isolated residential buildings in accordance with the TSDC-2018 without needing any particular academic or commercial software. A suite of differential equations using the design parameters is arranged to represent the overall dynamics of seismically isolated buildings. Disregarding the directivity effects in site-specific studies for the selected construction site in Antakya city center can result in large earthquake demands and careful attention should be given to reconstruction studies for urban planning and more detailed studies should be carried out including other complex mechanisms experienced during the 6 February 2023 Türkiye earthquake doublet. Full article

Background: Upper-limb performance in handball depends on accurate shoulder sensorimotor control under high loads and fatigue. This study examined between-cohort differences associated with concentric versus eccentric exercise-induced fatigue in shoulder proprioception, kinesthesia, functional stability, and isometric force output in professional male handball players. Methods: This was a retrospective, quasi-experimental (non-randomized) between-cohort comparison of two previously collected cohorts who completed either a concentric (n = 46) or eccentric (n = 33) fatigue protocol, with pre- and post-fatigue assessments of joint repositioning sense (absolute angular error, AAE), threshold to detection of passive movement (TTDPM), Y Balance Test Upper Quarter (YBT-UQ), and the Athletic Shoulder (ASH) test. Results: Fatigue significantly increased AAE across all tested angles (Time: all p < 0.001), with a contraction-specific effect at end-range internal rotation (IR45°), where AAE increased more after concentric than eccentric fatigue (Time × Fatigue Type: p = 0.017; Δ = +1.34° (+61.8%) vs. +0.20° (+7.4%)). TTDPM increased after fatigue (p = 0.001) with no interaction (p = 0.968). YBT-UQ performance decreased after fatigue for all dominant-limb outcomes and for non-dominant inferolateral, superolateral, and composite scores (all p ≤ 0.018), but not for non-dominant anteromedial reach (p = 0.986); no Time × Fatigue Type interactions were detected for YBT-UQ outcomes (all p > 0.05). ASH force output decreased across all positions and both limbs (all p ≤ 0.002), with the dominant-limb Y position showing a greater decline following eccentric fatigue (Time × Fatigue Type: p = 0.030; e.g., ASH Y dominant Δ = −0.49 (−4.6%) vs. −1.43 N·kg⁻¹ (−13.3%)). Conclusions: Exercise-induced fatigue impairs shoulder sensorimotor function and upper-limb performance in handball. Contraction-mode differences were small and task-specific in this between-cohort comparison, emerging primarily at end-range proprioception and selected isometric strength positions. These findings may inform the design of training programs that emphasize fatigue-resistant sensorimotor control and end-range strength, while causal inferences regarding contraction mode are not warranted given the non-randomized design. Full article

Background and Objectives: This study investigated the efficacy of eccentric isokinetic muscle strengthening versus passive motion protocols on neuromuscular function and performance capacity in female swimmers with chronic lateral epicondylitis. Materials and Methods: Twenty-five swimmers (age 46.1 ± 3.1 years) with lateral epicondylitis exceeding three months’ duration completed a randomized controlled trial comparing eccentric training in Controlled Active Motion mode (experimental group (EG), n = 13) against passive motion in Continuous Passive Motion mode (control group (CG), n = 12). Both groups performed 18 supervised sessions over six weeks (60°/s angular velocity, progressive loading 1–12 sets × 5 repetitions). Bilateral concentric peak torque of elbow extensors and flexors constituted the primary outcomes. Secondary measures included push-up performance, explosive power assessed by the Seated Medicine Ball Chest Push Test, and goniometric range of motion. Linear mixed-effects models and analysis of covariance with baseline adjustment were employed. Results: Eccentric training produced side-specific strength adaptations in elbow flexors (confirmed interaction: F_1,23 = 8.56, p = 0.008, η_p² = 0.271), with the experimental group demonstrating balanced bilateral gains, whereas the control group exhibited asymmetric responses favoring the non-dominant limb. EG demonstrated superior functional gains: push-up repetitions increased 4.15 ± 1.77 versus 2.17 ± 1.27 in CG (adjusted difference = 3.21 repetitions, 95% CI [1.52, 4.90], p = 0.001, d = 1.31), while explosive power improved 0.32 ± 0.09 m versus 0.10 ± 0.06 m (adjusted difference = 0.35 m, 95% CI [0.25, 0.45], p < 0.001, d = 1.20). Range of motion remained unchanged across groups (all p > 0.65). Conclusions: Eccentric isokinetic strengthening confers substantial advantages over passive motion protocols for restoring upper-body muscular endurance and ballistic force production in swimmers with lateral epicondylitis, supporting its integration into rehabilitation frameworks for the management of tendinopathy. Full article

Background: Group A Streptococcus (GAS) induces a wide spectrum of human diseases, ranging from superficial infections to life-threatening invasive conditions and post-infectious sequelae such as rheumatic heart disease, posing a heavy global health burden. Critically, there is still no licensed commercial vaccine against GAS, making the development of novel, effective vaccines against this pathogen an urgent and crucial unmet medical need. Methods: We developed a dual-antigen nanoconjugate vaccine against GAS. The Group A Carbohydrate polyrhamnose backbone (GAC^PR) and truncated SLO were site-specifically conjugated via Protein Glycan Coupling Technology (PGCT) in engineered E. coli, and then linked to ferritin nanoparticles using the SnoopTag/SnoopCatcher system. Safety, immunogenicity, and protective efficacy were evaluated in murine models. Results: The nanovaccine was successfully synthesized with high purity. It elicited robust GAC- and SLO-specific IgG/IgG1 responses, conferred 90% survival against lethal GAS challenge (vs. 0–50% in controls), reduced bacterial loads in organs, and lowered inflammatory cytokines. Passive immunization with vaccine-induced serum also achieved 90% survival. No abnormal biochemical indicators, inflammatory responses, or organ pathology were observed. Conclusions: This study successfully developed a bivalent nanoparticle vaccine against GAS. This novel nanovaccine exhibits excellent safety, strong immunogenicity, and effective protection against GAS, providing a promising vaccine candidate. Full article

To address the limitations of existing quarter-vehicle models in capturing pitch motion and front-rear coupling effects, this paper proposes a half-vehicle mechatronic suspension system based on the electromechanical analogy. Traditional methods often overlook non-ideal effects and the dynamic interaction between the front and rear wheels. This paper constructs an equivalent electrical network model for the half-vehicle suspension system. To ensure the physical realizability of the system, parameter optimization is performed under positive-real constraints using the Non-dominated Sorting Genetic Algorithm II (NSGA-II). This approach achieves an optimal trade-off between vertical vibration suppression and pitch control. Simulation results under random road input at a vehicle speed of 20 m/s indicate that while the unconstrained mechatronic suspension improves ride comfort, it increases the dynamic tire load by 19.18%. In contrast, the constrained mechatronic suspension reduces RMS vertical body acceleration by 19.54% and pitch angular acceleration by 2.22% compared to the standard passive suspension. Additionally, a reduction of 8.29% was observed in the suspension working space RMS, alongside a 1.26% decrease in the dynamic tire load. These results demonstrate that introducing appropriate positive-real constraints effectively balances ride comfort and road-holding performance, providing a systematic modeling and optimization framework for half-vehicle mechatronic suspensions. Full article

Heavy metal pollution is characterized by long-term accumulation and recalcitrance to degradation, which poses a serious threat to soil ecosystems and groundwater environments. To improve the remediation efficiency of biochar for cadmium (Cd)-contaminated soil, this study took unmodified biochar (BC) as the control and systematically explored the remediation potential of NaOH–KMnO₄–FeCl₃ composite-modified biochar (GBC). Combined with a Brassica napus L. pot experiment, the effects of modified biochar on soil Cd passivation, soil physicochemical properties, and B. napus biomass were analyzed. After composite modification, GBC had its surface ash removed and exhibited a more regular pore structure, with successful loading of iron–manganese oxides. Although partial changes in the microporous structure caused a decrease in CO₂ adsorption, the number of surface-active sites increased. Both biochars significantly increased soil carbon content, nitrogen and phosphorus nutrient levels, and electrical conductivity, while promoting B. napus biomass accumulation and reducing its Cd enrichment. Among them, the GBC-1.5 treatment group exhibited the most significant increase in B. napus biomass, which was 33.66% higher than that of the control group (CK). However, soil pH increased with the increase in BC but decreased with the increase in GBC application rate. In terms of Cd passivation effect, both biochars showed excellent remediation performance. When the application rate was 3%, the Cd passivation rate of the GBC-3 treatment group reached 35.87%, which was 5.29% higher than that of the BC-3 treatment group. The loading of iron–manganese oxides further enhanced the effectiveness and stability of chemical adsorption. This study provides an important reference for achieving sustainable utilization of soil heavy metal remediation. Full article

This study presents a fault-tolerant control framework for an EMA-based active suspension under yaw-rate and roll-rate sensor faults. Instead of deactivating active suspension functions in the presence of sensor failures, the proposed approach maintains vertical load redistribution within feasible operating conditions. A hierarchical control structure is employed, integrating a multi-residual-based fault detection and isolation scheme with sensor-reliability-based control reconfiguration. The EMA is modeled at the force level, enabling direct integration into vehicle-level dynamics without explicitly modeling internal electrical dynamics. The proposed method is evaluated using ISO 3888-1 double lane change simulations, where peak tire vertical forces and combined tire forces are used as performance metrics. Simulation results indicate that the proposed framework mitigates excessive load concentration compared to passive suspension under sensor fault conditions. Full article

This paper presents a patented design of a gravity flow rack with an energy recovery system, intended for pallet storage in first-in–first-out (FIFO) and last-in–first-out (LIFO) modes. Compared with conventional flow racks, the proposed solution integrates control of load-unit motion dynamics with energy recovery, thereby reducing losses and stabilising pallet flow. A Rack Energy Performance Index (REPI) is proposed to enable quantitative assessment of the energy consumption of storage racks in intralogistics applications. The research methodology comprised: (i) development of the mechanical architecture and pallet guidance principles; (ii) numerical modelling in the MSC Adams environment at Technology Readiness Level 3 (TRL-3); and (iii) validation using a full-scale prototype installed in a logistics centre. Operational tests confirmed stable operation, the required throughput, and the capability for energy compensation and recovery during storage cycles. The results indicate that energy-recovering racks can support the design of energetically passive warehouses. Full article

Advance hydraulic supports are widely applied in deep coal mine roadways; however, inappropriate initial support force often leads to either insufficient roof control or over-support, weakening the effectiveness of bolt–cable systems. To clarify the interaction mechanism between advance passive support and active bolt–cable reinforcement, an advance roadway support model was developed using FLAC3D based on the geological conditions of the 1432 working face in the Dongtan Coal Mine. Numerical simulations were conducted by varying the initial support force from 0 to 14 MPa, and the corresponding roof displacement, bolt stress, and cable axial force responses were systematically analyzed. The results indicate that roof subsidence decreases nonlinearly with increasing support force, exhibiting a rapid suppression stage (0–10 MPa) and a stable coordination stage (10–12 MPa). Within this optimal range, load transfer from the roof to the passive support is significantly enhanced, leading to effective stress relief and homogenization in the bolt–cable system. When the support force exceeds 12 MPa, further deformation control becomes marginal, indicating a transition from cooperative load sharing to over-support. These findings reveal the staged interaction mechanism between advance passive support and active reinforcement systems, providing a quantitative basis for selecting appropriate initial support force in deep roadway engineering. Full article

As the oil price has skyrocketed, the attraction towards electric vehicles has gone up. This scenario has also increased the demand for charging infrastructure. This paper proposes a novel charging infrastructure for electric vehicles which is energized by a solar photovoltaic unit, integrated with a distribution static compensator. The output of the photovoltaic array is regulated by a DC–DC converter, which uses maximum power point tracking to support optimal solar energy conversion. The compensator is integrated into the grid through a zigzag-star transformer, which helps with neutral current compensation, promoting balanced and distortion-free operation. The control algorithm is designed to ensure superior power quality during grid synchronization and sustainable energy management. This novel architecture ensures bidirectional power flow, enabling the charge–discharge dynamics of the electric vehicles, which can be termed Grid-to-Vehicle and Vehicle-to-Grid modes. Better grid flexibility and resilience are ensured by this dynamic power exchange. The control strategy based on the Linear Kalman Filter provides reactive power balance and maintains steady voltage at the point of common coupling, and it ensures enhanced power quality during power flow, resulting in efficient and reliable grid operations. The effectiveness of the control algorithm is tested and validated under Grid-to-Vehicle, Vehicle-to-Grid, nonlinear, unbalanced, and isolated solar conditions. Analytical tuning of the gains in the controller, by using the conventional methods, is not efficient under dynamic conditions and nonlinear loads. An optimization technique is used to estimate the proportional–integral control gains, which avoids the difficulty of tuning the controllers. Simulation of the system is carried out using MATLAB 2022b/SIMULINK. Simulation results under diverse operating scenarios confirm the system’s capability to sustain superior power quality, maintain grid stability, and support a robust and reliable charging infrastructure. By enabling regulated bidirectional energy exchange and autonomous operation during grid disturbances, the charger operates as a resilient grid-support asset rather than as a passive electrical load. Full article