Search Results (360)

Multi-infeed LCC-HVDC siting requires a static strength test, a finite-fault propagation assessment, and an auditable rule for selecting the subset of candidates that receives detailed electromagnetic-transient (EMT) evaluation. This paper develops a directional fault-response matrix whose row denotes the responding converter bus and whose column denotes the fault-source terminal. A two-infeed derivation, stated for scalar or common-angle impedances and checked numerically for unequal $X/R$ ratios, shows that a stronger inter-bus tie can raise the weaker terminal’s simplified MSCR while increasing the mutual impedance and the cross-terminal fault response. Structural properties of the nonnegative matrix are derived, and a closed-form first-order surrogate calibrated by one pooled least-squares gain screens all 15 four-infeed combinations of six synthetic sites and routes seven candidates (28 single-source switching-EMT runs) to detailed verification. The complete 60-run library is additionally simulated offline and used only as ground truth: the reduced and EMT composite scores have Spearman coefficients of 0.750 over the routed set and 0.911 over all 15 candidates (0.911 under leave-one-candidate-out calibration), the reduced hard screen produces zero false retentions and zero false rejections, and the matrix score is compared with MSCR-only and impedance-ratio MIIF baselines. ABCE is the best verified candidate, with a minimum simplified MSCR of 2.008 and a maximum EMT cross-response of 0.0395 p.u. A 0.05 ohm stress profile activates the transient limit for 9 of the 15 candidates. Element-level error, weight and threshold sensitivity, measured simulation times, and model limitations are reported. The method remains a screening and diagnostic framework rather than a stability law or a proof of global EMT optimality. Full article

This study evaluated the long-term changes induced by wearing minimalist footwear (MF) during activities of daily living (ADLs) on the plantar footprint and postural stability in healthy adults. In this randomized clinical trial, a total of 95 healthy adults were recruited; 90 participants completed the protocol and were analyzed in either an experimental group (EG, n = 45), which wore MF for at least 5 h per day over a 6-month period, or a passive control group (CG, n = 45). Plantar pressure distribution (forefoot, rearfoot, and total contact areas), static stability (center of pressure (CoP) displacement under open-eyes and closed-eyes conditions), and dynamic stability (forward reach test) were assessed using a force platform at baseline and post-intervention. A self-reported questionnaire and an adverse event record were also completed by the EG. Statistical analysis was carried out using a repeated-measures analysis of variance (ANOVA) and a paired Student’s t-test; statistical significance level was set at p < 0.05. The Group $\times$ Time interaction analysis revealed no statistically significant between-group differences across the evaluated parameters. However, within-group analysis showed a significant increase in CoP displacement under the open-eye condition in the CG ($p=0.037$), indicating a decline in baseline postural efficiency, whereas the EG maintained structural and posturographic stability. Regarding user feedback, comfort (44.4%) was highlighted as the primary advantage, aesthetics (77.8%) was the main drawback, and 70% of the participants intended to continue using MF. Only two minor, transient adverse events were recorded. In conclusion, a 6-month program of MF use during ADLs did not produce any statistically significant changes in plantar footprint or stability in healthy adults. Full article

The functional expression of plant growth-promoting (PGP) traits in soil actinobacteria is conditioned by abiotic factors, yet the combined effects of pH and temperature on their metabolic profiles and the stability of these profiles after encapsulated formulation and post-processing stress remain insufficiently characterized. This study aimed to evaluate the physiological plasticity of native actinobacteria and the expression of plant growth-promoting (PGP) traits under different pH and temperature conditions, as well as their stability after encapsulation, dehydration, and exposure to UV irradiation. Strains isolated from a semi-arid agricultural soil were analyzed to determine their ability to produce indole-3-acetic acid (IAA), siderophores, and phosphatases, as well as their ability to fix nitrogen, degrade cellulose, and tolerate salt stress. Temperature and pH significantly affected all evaluated PGP traits (p < 0.001), and their expression was not directly associated with biomass production. Two strains, S1 and S4, exhibited the highest overall PGP indices. Strain S1 maximized IAA and siderophore production under neutral conditions (pH 7.0, 30 °C), whereas strain S4 maintained more stable phosphatase activity across the tested pH and temperature ranges. Cell viability remained above 85% after encapsulation and dehydration. Dehydration enhanced IAA and siderophore production in strain S1, while strain S4 exhibited transient metabolic activation under UV irradiation in non-dehydrated capsules. The encapsulation matrix preserved cell viability more effectively than it preserved the complete PGP functional profile, indicating that viability alone is an insufficient criterion for evaluating the technological success of alginate-based bioinoculant formulations. These findings highlight the importance of integrating environmental preconditioning and functional stability assessments into the development of robust microbial bioinoculants adapted to agricultural systems subjected to fluctuating environmental conditions. Full article

Rapid leakage prediction during pressure-reducing valve manoeuvres requires models that reproduce inertial hydraulic effects at low computational cost. This study proposes a reproducible surrogate-modelling framework in which transient leakage responses are generated with an extended rigid water column model incorporating time-dependent valve resistance and then used to train machine learning regressors. Twenty-eight regression models were evaluated using four SCADA-oriented predictors: time, inlet flow, upstream pressure head, and valve position. Model selection followed an accuracy–cost–predictive-stability assessment that considered predictive error, training time, inference speed, model size, and behaviour under near-domain, boundary-unseen, and extreme extrapolation scenarios. Gaussian process regression achieved the lowest in-domain errors, with test root mean square error values of 0.0017–0.0019 L/s, but required training times above 21,000 s and inference speeds below 700 observations/s. Bagged Trees provided the most balanced option for PRV-operation screening within the represented hydraulic domain, combining low prediction error, high inference capacity, and stable behaviour within the evaluated near-domain and boundary-unseen range. The P3 extrapolation test showed that prediction beyond the represented hydraulic envelope requires scenario-library expansion and model reassessment. The framework supports rapid valve-operation screening and numerical assessment of RWCM-generated transient leakage responses, while field or SCADA-supported use requires local calibration and validation. Full article

This study presents an experimental validation of an adaptive fuzzy logic controller (AFLC) for solar-driven proton exchange membrane (PEM) hydrogen production under dynamic operating conditions. The proposed solar-driven PEM hydrogen production system was accurately modeled and investigated under various operating conditions using the MATLAB/Simulink simulation platform. In order to evaluate the effectiveness of the proposed controller, the AFLC strategy was experimentally investigated using a dSPACE DS1104 platform and compared with conventional Proportional–Integral (PI) and Fuzzy Logic Controller (FLC) approaches in terms of tracking accuracy, transient response, overshoot suppression, current ripple minimization, and overall hydrogen production stability. Under step-change solar irradiance conditions, the proposed AFLC exhibited superior MPPT performance, achieving improvements of 34.32% and 84.26% in power-tracking accuracy compared with the conventional FLC and PI controllers, respectively. The developed control architecture employs real-time feedback from electrolysis to regulate the duty cycle of the DC–DC converter controlled by maximum power point tracking (MPPT), ensuring precise power delivery to the PEM electrolysis despite fluctuating solar irradiance. Additionally, the solar hydrogen production system’s performance indices were computed. These indices are intended to assess the viability of the AFLC in comparison to the PI and FLC under the same solar irradiance conditions. Full article

Congenital and developmental cervical spine variants, as well as acquired or sport-adapted cervical morphologies, may alter canal reserve, segmental stability, foraminal dimensions, and the cervicothoracic outlet in athletes. This narrative review aimed to integrate the anatomically and methodologically heterogeneous literature linking these findings with sports-related injury and return-to-play decisions. PubMed/MEDLINE was searched from database inception through 6 July 2026 using controlled vocabulary and free-text terms for cervical anatomy, specific variants, athletic exposure, neurological syndromes, injury mechanisms, and return to sport; reference lists of relevant publications were also examined. English-language human studies were selected for direct anatomical, biomechanical, clinical, or athlete relevance and synthesized by evidence type, mechanism, vertebral level, and sport. The strongest athlete-specific evidence concerned developmental or functional cervical stenosis, space available for the cord, cervical cord neurapraxia, transient quadriparesis, and stingers in collision sports. Evidence for atlas arch defects, os odontoideum, Klippel–Feil syndrome, cervical spondylolysis, and cervical rib-related thoracic outlet syndrome was predominantly case-based or derived from expert guidance. These findings support cautious, individualized interpretation rather than universal clearance rules. Clinical assessment should integrate symptoms, neurological findings, imaging, dynamic stability, recurrence, and sport-specific exposure while recognizing that prospective athlete-specific evidence remains limited. Full article

Advanced treatment of plant effluent (tailwater) is critical for mitigating agricultural non-point source pollution; however, plant–substrate synergy in vertical-flow constructed wetlands (VFCWs) remains poorly understood under subtropical conditions. This one-year pilot study evaluated the effects of substrate type (zeolite vs. gravel) and P. australis presence on nutrient removal, seasonal performance stability, and microbial community assembly in tailwater treatment. Methodologically, twelve VFCWs were operated across seasons, and their performance was assessed via water quality monitoring and high-throughput sequencing. The results indicate that all configurations consistently met stringent discharge standards. Planted treatments significantly outperformed unplanted controls in removing TN, COD, and TP (p < 0.05), while no significant difference emerged between zeolite- and gravel-planted systems, confirming vegetation’s dominance over substrate selection under low-concentration loads. Seasonal analysis revealed temperature-dependent TN removal (p < 0.01), whereas TP, COD, and NH₄⁺-N removal remained stable. Microbial analysis showed P. australis selectively enriched functional taxa driving N and organic matter mineralization despite a shared core microbiome at the genus level. Gravel-planted VFCWs exhibited superior long-term resilience compared to the transient sorption of zeolites. We considered that vegetation-driven biological pathways offer a resilient design for polishing nutrients in tailwater, showing potential for agricultural irrigation and nutrient interception. Full article

Background: The tick microbiome is shaped by environmental filters and host biological traits. Microbial co-occurrence networks offer a powerful framework to map inter-microbial interactions, node topological roles, and community stability beyond standard diversity metrics; however, how tick sex modulates these structural networks remains poorly understood. Methods: We sequenced the V3–V4 variable region of the 16S rRNA gene from 86 adult Hyalomma lusitanicum ticks (37 males and 49 females) collected across six ecogeographical localities in Andalusia during 2023. A refined dataset of 5570 high-confidence Amplicon Sequence Variants (ASVs) was analyzed. Alpha and beta diversity patterns were evaluated using PERMANOVA models, and sex-stratified co-occurrence networks were constructed using Spearman’s rank correlations and the Zi-Pi topological framework to assess network complexity and keystone roles. Results: The primary obligate endosymbiont Francisella dominated the bacteriome (60–90% relative abundance), followed by Candidatus Midichloria. PERMANOVA models confirmed that geographical locality (R² = 0.111, p = 0.003) and host sex (R² = 0.095, p = 0.001) exerted strong, independent influences on microbial composition. Female ticks harbored a highly streamlined bacterial profile. Conversely, males exhibited significantly higher alpha diversity (p < 0.001), reflecting host-sex physiological and behavioral differences that create a broader ecological niche allowing diverse environmental and transient taxa (Acinetobacter, Sphingomonas, Stenotrophomonas, Brevundimonas) to colonize. Network analysis revealed a striking sexual dimorphism: female networks were highly centralized and anchored by a single global hub (Roseomonas), whereas male networks lacked global hubs and displayed higher topological complexity, achieving stability through a decentralized architecture sustained by 68 inter-module connectors (compared to 24 in females). Despite these macro-topological differences, a core set of seven connector ASVs was conserved across both sexes. Conclusions: These findings demonstrate that host sex shapes the ecological niche of the tick microbiome and drives distinct network topological strategies to maintain community stability, providing new insights into the structural ecology of tick–microbe interactions. Full article

Background/Objectives: Closed reduction and percutaneous pinning is the standard surgical treatment for displaced pediatric supracondylar humerus fractures. Although crossed-pin fixation provides excellent biomechanical stability, medial pin insertion remains associated with the risk of iatrogenic ulnar nerve injury. The modified medial para-olecranon technique has been introduced as an alternative medial wire insertion strategy while preserving the principles of crossed-pin fixation. This study compared its clinical performance with conventional crossed pinning. Methods: A retrospective comparative cohort study was conducted at a tertiary referral trauma center between January 2017 and December 2024. Seventy children younger than 14 years with Gartland type II–IV supracondylar humerus fractures met the inclusion criteria. All patients treated with the modified medial para-olecranon technique (n = 35) were included. A comparison cohort of 35 patients treated with conventional crossed pinning was selected from 68 eligible conventionally treated patients by computer-generated random sampling stratified by Gartland type (frequency matching), after application of identical eligibility criteria. The primary outcome was functional outcome assessed using the Flynn criteria. Secondary outcomes included operative time, radiographic alignment, fracture union, and postoperative complications. Results: Baseline demographic and fracture characteristics were comparable between groups. Mean age was 6.7 ± 2.8 years in the modified medial para-olecranon group and 6.9 ± 2.6 years in the conventional crossed-pin group. The modified medial para-olecranon group had a lower mean Flynn score (6.80 ± 3.31 vs. 10.74 ± 3.70; mean difference, −3.94; 95% CI, −5.61 to −2.27; p < 0.001) and a higher proportion of excellent Flynn outcomes (77.1% vs. 28.6%). Operative time was shorter in the modified medial para-olecranon group (47.49 ± 7.50 vs. 66.00 ± 8.19 min; mean difference, −18.51 min; 95% CI, −22.26 to −14.76; p < 0.001). Fracture union occurred at a comparable time in both groups (27.71 ± 3.94 vs. 28.34 ± 4.12 days; mean difference, −0.63 days; 95% CI, −2.55 to 1.29), and postoperative Baumann angles were similar. No postoperative iatrogenic ulnar nerve injuries occurred in the modified medial para-olecranon group, whereas two occurred in the conventional crossed-pin group; both were transient sensory paraesthesia that resolved without exploration within six months. Overall complications occurred in 1 patient (2.9%) and 7 patients (20.0%), respectively (odds ratio, 0.17; 95% CI, 0.03 to 1.02; Fisher exact p = 0.055). Conclusions: In this retrospective comparative cohort, the modified medial para-olecranon technique was associated with favorable functional outcomes, shorter operative time, and fewer observed postoperative ulnar nerve injuries, although the difference in complications did not reach statistical significance, while maintaining comparable radiographic alignment and fracture healing. Because treatment was not randomized and potential confounders could not be adjusted for, these between-group differences should be interpreted as associations rather than as evidence of a causal treatment effect. Further prospective multicenter studies and dedicated anatomical investigations are required before broader recommendations can be made. Full article

Ultra-supercritical (USC) steam turbines combine severe steam conditions with increasingly frequent start-up, shutdown, and load-following operations. Their main steam valves must preserve pressure boundary integrity, sealing, and rapid actuation while non-uniform heating, creep, cyclic plasticity, oxidation, wear, and contact redistribution alter component geometry. However, the relevant evidence remains fragmented across alloy development, component thermo-mechanics, valve aerodynamics, and lifetime monitoring. This short, mechanism-oriented review integrates these domains through a material structure–function framework in which deformation relative to assembly clearance governs jamming risk. It synthesizes evidence on heat-resistant body and surface materials, 9–12% Cr steel stability, weldability and repair sensitivity, and cold, warm, and hot start-up histories. It also evaluates creep–fatigue interaction, contact, flow-induced vibration, multi-physics modeling, validation, uncertainty, monitoring, and digital twins. The synthesis shows that neither peak equivalent stress nor steady-state temperature alone can establish functional reliability. Credible assessment requires temperature-dependent material data, realistic steam-side heat transfer, cyclic constitutive behavior, initial and residual clearances, manufacturing and assembly tolerances, state-dependent friction, uncertainty analysis, and corroborating plant or inspection evidence. The most consequential research needs are valve-level validation datasets, thermal contact testing, function-oriented life criteria, and uncertainty-aware digital twins that jointly inform materials, geometry, and transient operation. Full article

The massive integration of “hydro–wind–solar hybrid” generation transmitted via AC/DC hybrid grids with High-Voltage Direct Current introduces unprecedented challenges to power system transient stability. Traditional Dynamic Security Assessment heavily relies on time-domain simulation and high-density Monte Carlo sampling, which suffer from massive computational burdens and are strictly prohibitive for intra-day operational dispatch. To address this long-standing bottleneck, this paper proposes a novel data-driven comprehensive security region assessment framework based on an Active Learning query strategy and a Support Vector Machine surrogate model. By seamlessly coupling Python with the DIgSILENT PowerFactory simulator, the proposed AL algorithm actively queries and evaluates only the critical operating points near the stability margin, effectively avoiding redundant simulations in obviously safe or unsafe zones. Extensive simulations under a severe N-1-1 contingency demonstrate that the proposed framework can accurately map the non-linear boundaries of both transient rotor angle and short-term voltage stability constraints. Furthermore, the framework’s scalability is rigorously validated in complex 3D high-dimensional operational spaces. By integrating an ϵ-greedy exploration strategy with a Label Flip Rate (LFR) early stopping criterion, the proposed algorithm successfully overcomes the curse of dimensionality. Quantitatively, the proposed method achieves nearly identical boundary resolution using merely 65 physical simulations, as opposed to the 40,000 evaluations required by conventional high-density grid scanning. The total computational time is drastically reduced from 28.6 h to approximately 2.8 min, yielding a remarkable acceleration of over 600 times, making it highly suitable for near-online dynamic security monitoring. Full article

Background and Objectives: Angular and rotational lower limb alignment concerns are a frequent reason for paediatric consultations. In most children, these findings reflect physiological developmental patterns that resolve spontaneously, but unilateral, progressive, or symptomatic cases may indicate pathology and require specialist assessment. Materials and Methods: This narrative review summarizes clinically relevant developmental norms, key elements of history and physical examination, common differential diagnoses, and practical indications for imaging and referral, with the objective of offering a structured clinical guidance framework for primary care and paediatric practitioners. Results: Physiological coronal plane lower limb alignment typically progresses from infant genu varum to neutral alignment by around 2 years, followed by transient genu valgum between 3 and 6 years, and stabilizes by approximately 7–8 years. Rotational alignment changes predictably with growth and most commonly presents as in-toeing due to femoral anteversion, internal tibial torsion, or metatarsus adductus. Out-toeing is less often physiological and should prompt careful evaluation for underlying disorders, including slipped capital femoral epiphysis. Clinical assessment should prioritize gait observation, foot progression angle, hip rotation, and thigh–foot angle, while imaging should be reserved for atypical presentations, asymmetry, progression, pain, or suspected systemic or neuromuscular disease. Conclusions: Most paediatric lower limb alignment “abnormalities” represent normal variants and require reassurance and observation. Recognizing age-appropriate patterns and red flags enables paediatricians to limit unnecessary interventions while ensuring timely referral and treatment for pathological conditions. Full article

Mixed mode I–III fracture commonly occurs in rock masses under complex three-dimensional stress states, yet the combined effects of loading conditions and fracture mode remain unclear. In this study, a heterogeneous sandstone disc model is developed in ABAQUS by coupling the Drucker–Prager elastoplastic model, an equivalent-strain damage model, and cohesive elements. The model is validated against static Brazilian splitting tests and dynamic SHPB tests. ENDB specimens are then employed to investigate mode I, mode III, and mixed mode I–III fracture under static and dynamic loading with offset angles ranging from 0° to 62.5°. As the offset angle increases, crack propagation evolves from straight tensile extension to deflected, twisted, and fragmented patterns dominated by anti-plane shear. Dynamic loading intensifies crack segmentation, localized damage, and transient instability while increasing the peak load, fracture toughness, and fracture energy. In contrast, the effective fracture toughness and fracture energy decrease monotonically with increasing offset angle under both loading conditions. A linear trend consistent with R² > 0.99 is observed between the mode I–III mixing coefficient and the effective fracture toughness based on single-realization simulations, the effective fracture toughness under dynamic loading is approximately 2.22 times that under static loading based on direct comparison of calculated values. These findings improve the understanding of loading-dependent mixed mode I–III fracture in sandstone and provide guidance for rock mass stability assessment. Full article

This paper presents an advanced load frequency regulation strategy for interconnected thermal power systems integrated with renewable energy sources and energy storage systems. A two-area non-reheat thermal power system is investigated, where photovoltaic generation is incorporated in Area 1 and wind turbine generation in Area 2 to assess the impact of renewable penetration on system dynamics and frequency stability. To improve the dynamic response under varying operating conditions, a novel multi-stage TDn(1+PIDn) controller is proposed. The TDn stage enhances transient shaping, while the PIDn stage provides superior damping and steady-state accuracy. The controller parameters are optimally tuned using the pied kingfisher optimizer (PKO) and compared with particle swarm and grey wolf-based optimizers. Furthermore, vanadium redox flow batteries, superconducting magnetic energy storage, and hydrogen–air fuel cells are integrated into the hybrid system to mitigate frequency oscillations caused by renewable intermittency. Offline simulations and real-time validation using the OPAL-RT OP4512 simulator are conducted under different dynamic scenarios. The obtained results demonstrate that the proposed PKO-TDn(1+PIDn) method achieves the best transient performance, for example, reducing the $∆F_1$ overshoot, undershoot and settling time by 28%, 15% and 7.5%, respectively, relative to its closest-performing counterpart while attaining the minimum ITAE value of 0.037309. Consistent improvements are observed across the key performance metrics, confirming the robustness and effectiveness of the scheme for modern hybrid power systems. Full article

To address the insufficient feature representation of conventional data-driven transient stability assessment (TSA) models and their limited adaptability to changes in power-system operating conditions, which result in inadequate assessment accuracy, this paper proposes a TSA method based on high-level sample feature extraction and model updating. First, a self-supervised contrastive random feature perturbation model for transient stability assessment, called TSA-SCRF, is developed. By introducing random perturbations into steady-state power flow features and employing contrastive learning, the proposed model extracts robust deep feature representations while preserving fault-type information. Second, a boundary-aware ensemble support vector machine (BAESVM) is constructed, which exploits multiple kernel functions to learn complementary discriminative information and dynamically assigns classifier weights according to both classifier performance and the samples’ decision distances. Finally, high-value newly acquired samples are selected based on sample uncertainty and, together with the support vectors of the original model, are utilized for model updating. Case studies conducted on a provincial power grid in China demonstrate that the proposed method improves the accuracy of data-driven transient stability assessment and enhances the model’s adaptability to changes in power-system operating conditions. Full article