Search Results (309)

This study compared the kinematic and neuromuscular characteristics of the tennis forehand drive between high-performance (HP) and intermediate (INT) players. Eighteen right-handed male players (HP: n = 9; INT: n = 9) performed cross-court forehands while three-dimensional motion capture and surface electromyography (EMG) were recorded from the dominant upper limb and trunk. Kinematic and EMG data were time-normalized to the forward swing. One-dimensional statistical parametric mapping two-sample t-tests were used to compare joint angles, angular and linear velocities, and EMG amplitude waveforms between groups. Bonferroni-corrected significance levels were set at α = 0.0017 for kinematic variables and α = 0.0063 for EMG data. HP players exhibited greater racket linear velocity during the final part of the forward swing, accompanied by higher shoulder, elbow and wrist linear velocities, whereas hip linear velocity did not differ between groups. Joint angles were broadly similar, with SPM revealing only slightly greater early knee flexion in HP players. In contrast, HP players showed higher hip and knee angular velocities and greater wrist angular velocities in both flexion/extension and radial/ulnar deviation towards impact. EMG patterns were generally comparable, but HP players displayed higher biceps brachii activation in two significant clusters during the mid-to-late forward swing and greater triceps brachii activation in the late forward swing. No significant differences were observed for deltoid, pectoralis major, latissimus dorsi, flexor carpi radialis or extensor carpi radialis. These findings indicate that superior forehand performance in HP players is associated primarily with refined segmental coordination, greater lower-limb and distal segment velocities, and locally increased elbow muscle activation, rather than with widespread increases in upper-limb or trunk muscle activity. Full article

With the integration of renewable energy into traction power supply systems at a high proportion and penetration level, the intermittency and randomness of renewable energy output significantly intensify the fluctuation characteristics of traction loads, posing severe challenges to the stable operation and precise dispatch of the system. To effectively address the dynamic tracking and anti-disturbance issues arising from the dual uncertainties of source and load, this paper proposes a dual-timescale two-layer optimization dispatch strategy based on Model Predictive Control (MPC). In the upper-layer optimization, with the objective of optimal system economic operation, a multi-step rolling optimization method is adopted to formulate a long-timescale baseline dispatch plan, fully considering the temporal correlation of photovoltaic and wind power outputs and the periodic characteristics of traction loads. In the lower-layer optimization, aimed at smoothing power fluctuations and correcting prediction deviations, the technical advantages of supercapacitors—high power density and fast response—are utilized to perform real-time tracking and dynamic compensation of the upper-layer baseline plan. This effectively reduces the impact of prediction errors on control accuracy, achieves smooth control of tie-line power, and enhances overall system stability. Case study results based on an actual railway traction power supply system demonstrate that the proposed method can fully leverage the coordinated and complementary characteristics of the hybrid energy storage system, effectively suppress power fluctuations from renewable energy output and traction loads, and achieve economic operation objectives while ensuring system disturbance rejection performance, thereby validating the effectiveness and practicality of the strategy. Full article

Understanding the spatiotemporal streamflow patterns under future climate scenarios is critical for sustainable water resource management in large river basins. This study applied the Soil and Water Assessment Tool (SWAT), forced by five downscaled and bias-corrected CMIP6 global climate models, to evaluate historical (2008–2024) and future (2025–2049) streamflow patterns in the Missouri River Basin in the continental United States. Model calibration and validation were satisfactory, with NSE > 0.5, KGE ≥ 0.5, R² > 0.5, and PBIAS within ±25% at most USGS gauge stations. Future projections indicate spatially and temporally variable hydrological responses: The upper basin (Bismarck, North Dakota) is projected to experience lower flows across most percentiles and reduced extreme events, whereas the lower basin (Hermann, Missouri) shows decreased median flows but higher extremes. Recurrence interval analysis of 2-, 5-, 10-, 50-, 100-, and 500-year flows suggests that 100-year flows may decline by 11% at Bismarck and increase by 37.4% at Hermann. These results highlight the importance of integrating percentile-based and extreme event streamflow analyses with hydrologic modeling for assessing the spatiotemporal streamflow patterns under future climate scenarios in large-scale basins. Quantitative insights into future streamflow variability and its implications for flood risk mitigation, water resources management, and adaptive strategies were gained for one of North America’s largest river systems. Full article

This paper investigates a five-level active neutral-point-clamped (5L-ANPC) converter operating in rectifier mode with unbalanced DC-side loads, where neutral-point (NP) deviation may deteriorate grid-current quality. Conventional space-vector pulsewidth modulation (SVPWM) is typically derived under the split-capacitor-voltage symmetry assumption; when NP deviation occurs, fixed sector boundaries and ideal volt–second balance calculations can lead to sector misclassification and synthesis errors. To address this issue, an NP-aware SVPWM scheme is proposed by reconstructing sector criteria using real-time capacitor voltages and correcting the vector dwelling-time computation to improve modulation accuracy under imbalance. Based on the power-transfer mechanism, an average-power boundary condition is further derived to quantify the admissible upper/lower load power ratio that allows NP regulation without additional hardware, and its validity is examined under resistive-load cases. Moreover, for battery-type loads exhibiting voltage-source characteristics, the control objective is extended from voltage symmetry to controllable power/charge allocation by establishing a mapping between the small-vector duty ratio and the branch average-power ratio, with constrained online solution and smoothing to mitigate coefficient jitter. Experimental validation is conducted on an OPAL-RT OP5707-based hardware-in-the-loop platform, where both single-phase and three-phase 5L-ANPC systems are implemented according to different verification objectives. The derived boundary condition for resistive loads is examined in the single-phase system, while the proposed modulation and battery-load power-allocation strategy are verified in the three-phase system. The three-phase arrangement is adopted for the battery-load case in order to avoid the second-order power ripple inherent to single-phase operation. Full article

To address the inherent inaccuracies of the classical beam theory (which overestimates the flexural stiffness) and the “quasi-plane section method” (which neglects the shear deformation) in the deflection analysis of steel truss web–concrete composite beams, this study homogenizes discrete steel truss web members into a continuous steel web with equivalent thickness based on the strain energy equivalence principle. This homogenization is conducted under the assumption of fixed-end constraints for web members, thus establishing a sandwich laminated beam model. Incorporating the assumptions of zigzag axial displacement and layer-wise quadratic parabolic transverse shear stress, this study adopts the governing equations for static bending of composite beams derived via Hamilton’s mixed energy variational principle—this theory eliminates the need for an artificial shear correction factor, as the transverse shear stress naturally satisfies the zero boundary conditions at the upper and lower surfaces and the continuity condition at the interlayers. Analytical solutions for bending deflection under uniformly distributed loads are derived and validated against three-dimensional (3D) finite element (FE) models. The analysis results of a 45-meter-span beam demonstrate that the relative error in the maximum deflection of both simply supported beams and cantilever beams calculated by the proposed method is approximately 5%, which is significantly superior to the classical beam theory; the deflection induced by the zigzag effect at the mid-span of simply supported beams accounts for 15% of the total deflection, making it an indispensable key component in structural design. This method enables accurate deflection prediction and provides reliable technical guidance for the preliminary design of steel truss web–concrete composite beam bridges. Full article

Background/Objectives: Emerging evidence suggests the presence of associations in joint mobility along anatomically defined myofascial continuities, indicating that joint mobility may co-vary across anatomically distant regions. This study aimed to investigate the correlations between the active range of motion (ROM) of joints belonging to the same myofascial chain in healthy, physically active individuals. Methods: Active ROM was measured in 61 adults (21 males and 40 females) at joints contributing to four myofascial chains: the superficial front line (SFL), superficial back line (SBL), functional front line (FFL), and functional back line (FBL), using an inertial measurement unit. Partial Pearson’s correlation coefficients (r), controlling for sex, were calculated to examine the relationships between joint ROM values within lines, with statistical corrections applied when necessary. Results: Significant, yet weak to moderate in most cases, partial correlation coefficients were identified among joints in the upper SFL (0.32–0.44), the lower SBL (0.42–0.44), along the FFL (0.29–0.51), and between the lower segments of the BFL (0.48–0.60). Conclusions: While some joint ROMs within myofascial chains demonstrate weak-to-strong associations, overall interdependence appears mode- and region-specific. These findings suggest that factors beyond fascial continuity, such as neuromuscular control, joint structure, and movement habits, are likely to contribute to ROM variability. Full article

Background/Objectives: Orthodontic mini-implants have become indispensable in modern orthodontics due to their ability to provide absolute anchorage, independent of patient compliance. Our research aims to illustrate the versatility of mini-implants in addressing diverse biomechanical challenges across different planes of tooth movement (sagittal, transverse, and vertical) based on a retrospective clinical analysis. Methods: A retrospective analysis of orthodontic treatments performed with mini-implants (Dual Top and JS systems) was conducted, focusing on predefined biomechanical objectives and outcomes. The analysis encompassed distinct biomechanical applications, including incisor retraction and space closure using sequential direct and indirect anchorage; transverse and vertical correction of adult open bite through mini-implant–assisted rapid palatal expansion (MARPE) and molar intrusion; deep bite correction via simultaneous upper and lower incisor intrusion; and unilateral molar distalization using palatal skeletal anchorage. Results: Mini-implants provided stable, reproducible anchorage in all cases, enabling complex three-dimensional tooth movements with minimal side effects. Sequential reuse of the same mini-implants for both indirect and direct anchorage reduced treatment invasiveness and enhanced anchorage efficiency. Combined skeletal expansion and posterior intrusion allowed improved transverse and vertical control in adult open-bite presentations. Pure incisor intrusion was achieved without molar extrusion or incisor proclination, while unilateral molar distalization was effectively managed using palatal skeletal anchorage. Across all cases, mini-implants enhanced treatment efficiency, reduced the need for auxiliary appliances, and ensured predictable outcomes. Conclusions: Orthodontic mini-implants represent a highly versatile and minimally invasive anchorage system adaptable to a broad range of biomechanical situations. Their ability to provide stable, reusable, and site-specific anchorage supports efficient correction of complex malocclusions and reinforces their pivotal role in contemporary orthodontic practice. Full article

Objectives: This study aims to evaluate the predictability of Clear Aligner Therapy (CAT) in deep bite correction and Spee Curve flattening by comparing final intraoral scans with planned outcomes in ClinCheck. Methods: STL files from pre-treatment, post-treatment (first aligner cycle), and planned final positions of 18 patients (12 females; 6 males; mean age 30.9 ± 12.3 years) were analyzed. The software Medit Link (version 3.4.4) was used to measure overbite as the vertical distance between the incisal edges of the maxillary and mandibular central incisors and the Curve of Spee in both arches by drawing a reference line between the most distal molar and the central incisor on each side, recording the perpendicular distance from the distal cusp. Measurements were repeated on post-treatment and ClinCheck STL files. Data analysis was performed using a Student’s t-test (p = 0.05) to compare the expected and actual measure variations and intraclass correlation coefficient (ICC) to assess aligner predictability. Results: A significant discrepancy was observed in overbite correction (55% achieved), with a significant difference between expected and actual outcomes (p = 0.0001). Moderate differences were noted for the lower Spee Curve (62% achieved), while the upper Spee Curve showed 86% of the expected change. ICC values were moderate for overbite and lower Spee Curve, and good for the upper Spee Curve. Conclusions: ClinCheck overestimates deep bite correction. Upper Curve of Spee flattening is highly predictable, while the lower curve flattening has lower predictability. Full article

Background: This study assessed the long-term stability of dental arch changes achieved through clear aligner treatment in growing patients during the early mixed dentition stage. Methods: This retrospective study included 20 patients (mean age 8.3 ± 0.4 years) treated with clear aligners according to a standardized sequential expansion protocol. No additional auxiliaries, interproximal reductions, or retentions were used. Dental casts were collected at baseline (T0), end of treatment (T1), and two years post-treatment without retention (T2). Linear and angular measurements (arch width, molar and incisor torque, Henry’s angle, overjet, overbite, and Little’s index) were assessed on digital models. Friedman ANOVA and Wilcoxon signed-rank tests were applied (α = 0.05). Results: At T1-T0, significant transversal expansion was achieved in both arches (U6–6 mesial +2.1 mm; L6–6 mesial +2.4 mm; p < 0.05), with favorable torque changes and a reduction in overjet (−1.5 mm). From T1 to T2, only minimal, non-significant relapse was detected, except for a slight reduction in lower left molar torque (−1.1°). The T2-T0 comparison confirmed stable improvements in mesial intermolar widths (upper +2.0 mm; lower +1.6 mm), molar derotations, and overjets (−1.9 mm), with no significant loss of expansion or sagittal correction. Conclusions: Clear aligners in early mixed dentition achieved significant and stable dental arch modifications over a 2-year follow-up without the use of retention appliances. This therapeutic approach may represent a reliable interceptive option in growing patients. Full article

With the deployment of Hydrogen-enriched Compressed Natural Gas (HCNG) technology, establishing market mechanisms adapted to its physical characteristics is crucial for renewable energy accommodation. However, existing studies lack HCNG pricing mechanisms that reflect calorific value fluctuations and often overlook the dynamic carbon emission characteristics of Hydrogen Mixed Gas Turbines (HMGTs). To address these gaps, this paper proposes a hierarchical optimization framework for Integrated RES-NG Providers (IRNPs) participating in multi-type markets. In the upper level, a bidding model involving electricity, HCNG, hydrogen, and CEP-GEC joint markets is established. A dynamic HCNG pricing mechanism based on the Wobbe Index is introduced to capture composition variations, and a refined HMGT model based on the modified Arrhenius equation is employed to quantify combustion-emission physicochemical kinetics. The lower level formulates market clearing models for social welfare maximization, which are transformed into a Mathematical Program with Equilibrium Constraints (MPEC) via KKT conditions. Case studies demonstrate that: (1) the refined HMGT model captures the dynamic fluctuation of the carbon emission factor between 0.6074 and 0.6216, correcting the bias of traditional static models; (2) the introduction of the dynamic HCNG pricing mechanism significantly enhances flexibility, increasing the renewable energy accommodation rate from 90.47% to 100%; (3) IRNPs maximize profits through multi-market arbitrage, achieving a daily total revenue of ¥2.231 million, a 30.9% increase compared to participating only in electricity–gas markets; (4) The critical thresholds for cross-market arbitrage are identified, and hydrogen is diverted to the hydrogen market when prices exceed 9.6 ¥/kg and completely prioritized over HCNG blending when prices surpass 15.6 ¥/kg. Full article

Accurate and reliable current measurement is a key prerequisite for ensuring the safe operation of power systems. Conventional through-core and wound current transformers require power outage for installation or modification of line structures, which are plagued by high installation difficulty and cost, and fail to meet the digital development needs of smart grids. To address the demand for non-intrusive installation of current transformers, this paper proposes a non-intrusive current transformer with PCB coils in reverse-series connection. First, a magnetic coupling current calculation model is established to design a reverse-series double-layer coil structure, and a mathematical model of the equivalent circuit for the sensing and measurement system is constructed. The influence of circuit parameters on the output response is analyzed, yielding an optimization method for the system operating state and completing the hardware circuit design. Subsequently, a simulation model of the reverse-series double-layer coil is built to calculate and analyze the amplitude-frequency characteristics, steady-state and transient performance, as well as anti-interference capability of the transformer. The results demonstrate that the designed transformer, combined with an active integrating circuit, achieves an upper cutoff frequency of 13,169 Hz and a lower cutoff frequency approaching 0 Hz, which satisfies the requirements of wide-frequency measurement while ensuring high sensitivity and anti-interference capability. Finally, a current-sensing experiment platform is built for comparative verification with conventional invasive current transformers. Experimental results show that after correction with a proportional coefficient of 1.317, the fitting squared error is only 0.0038. The linearity remains excellent under different conditions with a wide dynamic measurement range, and the phase error is less than 15°. Within the range of 2–120% of the rated current, the ratio error is less than 0.9%, indicating high measurement accuracy. This study provides a new high-precision and convenient method for current measurement in smart grids. Full article

The growing penetration of Distributed Energy Resources (DERs)—such as photovoltaic generation, battery energy storage, electric vehicles, hydrogen technologies and flexible loads—requires advanced Energy Management Systems (EMS) capable of coordinating their operation and leveraging controllability to optimize microgrid performance and enable flexibility provision to the grid. When the physical, electrical, and economic system model is properly defined, the main sources of performance degradation typically arise from forecast uncertainty and temporal discretization effects, which propagate into sub-optimal schedules and infeasible setpoints. This paper proposes and tests a two-stage deterministic EMS architecture featuring rolling-horizon planning at an upper layer and fast local setpoint adaptation at a lower layer, jointly to reduce the impact of forecast errors and other uncertainties on the objective function. The first stage can be deployed either on the edge or in the cloud, depending on computational requirements, whereas the second stage is executed locally, close to the physical assets, to ensure timely corrective action. In the simulated cloud-executed planning case, moving from hourly to 15 min granularity improves the objective value from −49.39€ to −72.12€, corresponding to an approximate 46% reduction in operating cost. In our case study, the proposed second-stage local adaptation can reduce the mean absolute error (MAE) of the EMS performance loss by approximately 50% compared with applying the first-stage schedule without local correction. Results show that this two-stage hierarchical EMS effectively limits objective-function degradation while preserving operational efficiency and robustness. Full article

Background: Sarcopenia is defined by decreased muscle strength along with low muscle quantity or quality. The assessment of muscle strength may be performed by grip strength test or chair stand test (CST) and both of these tests are treated as equivalent tools for assessing muscle strength. Heart failure with preserved ejection fraction (HFpEF) contributes to the progression of sarcopenia, and it is left ventricular diastolic dysfunction (LVDd) which primarily leads to the development of HFpEF. The aim of this study was to examine the relationship of muscle strength with echocardiographic parameters of LVDd in patients with CKD and eGFR ≤ 29 mL/min/1.73 m² not treated with dialysis. Methods: The study samples consisted of 46 men with CKD stages G4–G5 not treated with dialysis: 23 participants with HGS < 27 kg and 23 individuals with HGS ≥ 27 kg. The assessment of muscle strength was provided by the hand grip strength (HGS) test and the five-times sit-to-stand test (FTSST). Transthoracic echocardiography was performed with the use of a convex probe in conjunction with a Logiq P6 ultrasound system. Results: In G4–G5 CKD patients, upper limb muscle strength did not correspond to lower limb muscle strength. Participants with prolonged FTSST had a lower mean value of septal e’ and higher mean E/e’ compared to individuals with correct both HGS and FTSST. Participants with correct HGS and prolonged FTSST had the lowest mean left ventricular ejection fraction (LVEF), as well as the lowest mean tricuspid annular plane systolic excursion (TAPSE). Conclusions: In G4–G5 CKD patients not treated with dialysis, HGS and FTSST are not equivalent and should not be used interchangeably. In this population, decreased muscle strength is associated with LVDd and FTSST is more sensitive than HGS in the prediction of LVDd. Low muscle strength is also associated with systolic function of the left and right ventricle in G4–G5 CKD patients not treated with dialysis. Full article

The study investigates the projected impact of climate change on water runoff in the upper Parsęta catchment, a postglacial lowland basin located in northwestern Poland. In the first step of the analysis, hydrological simulations for the period 2005–2022 were conducted using the Soil and Water Assessment Tool (SWAT). Model calibration and validation, performed in SWAT-CUP with the SUFI2 algorithm, yielded satisfactory performance (R² = 0.66–0.80; PBIAS = 0.43–13.87). Based on the calibrated model, projected simulations were performed for three future decades (2021–2030, 2031–2040, and 2041–2050) under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Climate input data were derived from the KLIMADA 2.0 national database, which was developed using down-scaled regional climate model output from the EURO-CORDEX ensemble and statistical bias-correction methods to generate high-resolution projections. Under RCP4.5, mean annual runoff increased by approximately 13–26%, while under RCP8.5, the changes were more variable, ranging from 2% to 28% relative to the 2011–2020 baseline. Seasonal analyses revealed enhanced autumn–winter runoff and lower spring–summer flows. The findings highlight that moderate climate forcing can lead to substantial alterations in hydrological regimes in postglacial lowland catchments, in certain decades comparable in magnitude to those projected under extreme forcing, underscoring the need for adaptive water management in northern Poland. Full article

This study, conducted in the framework of the LIAISE field campaign in NE Spain (May–September 2021), investigates how near-surface relative humidity influences early-stage rainfall characteristics when precipitation is most affected by temperature and relative humidity before rainfall onset. Two instrumented sites were examined, using disdrometers, Micro Rain Radar (MRR), C-band weather radar data, and automatic weather stations. Rainfall events were first classified as stratiform or convective using weather radar data based on a texture analysis of the reflectivity field. Then, only stratiform events were selected and further classified into dry and moist categories according to the upper and lower terciles of near-surface (2 m) relative humidity at the rainfall onset (dry < 54%; moist > 72%). Results show that during dry events, the time delay between the detection of precipitation at ~750 m above ground level (AGL) (by MRR or C-band radar) and its arrival at the surface (measured by the disdrometer) is consistently longer than during moist events, indicating possible evaporation of raindrops during their descent. Surface drop size distributions also differ: dry cases have generally fewer small drops (with diameters < 0.8 mm) but relatively more large drops, leading to higher radar reflectivity values despite similar surface rainfall amounts. However, reflectivity observed aloft by C-band radar and MRR does not present the dependence on relative humidity found at ground level. Findings reported here increase our understanding of the impact of low-level conditions on precipitation characteristics and microphysical associated processes and may contribute to improve correction schemes in operational weather radar quantitative precipitation estimates. Full article