Search Results (235)

The objective of this study is to recover the transient out-of-plane displacement field of clamped circular plates subjected to blast loading using a single high-speed camera, as a low-cost alternative to stereo Digital Image Correlation (DIC) for the specific class of axisymmetrical structural responses of circular plates. The dynamic response of thin metal plates to blast loading is a fundamental problem in protective structural design, traditionally investigated through DIC. Although it provides full-field displacement measurements with high spatial resolution, it requires stereo camera arrangements, controlled illumination, speckle pattern preparation, and elaborate calibration procedures that significantly increase experimental cost and complexity. This study introduces a monocular optical method applicable to axisymmetrically defined material testing applications, such as the response of circularly supported isotropic plates under a uniform impulsive load, to recover the transient out-of-plane displacement field without using DIC. Clamped circular aluminum plates are subjected to blast loading generated by PG-3 charges of variable mass detonated at the closed end of a shock tube, with the exposed face matching the tube cross-section so as to enforce axisymmetric pressure load. A diametral reference line marked on the rear face of each specimen was recorded by a single high-speed camera, and a perspective correction derived from the axisymmetric deformed geometry was then applied to reconstruct the time-resolved displacement profile along the diameter. The permanent post-test deformed shape of each plate was subsequently digitized through 3D scanning and used as ground truth to validate the optical reconstruction. The reconstructed profiles closely matched the scans: for the conventional responses the root-mean-square error was 1.251 mm with a normalized mean residual of 6.57% (Case A) and 1.793 mm (9.20%, Case B), while for the anomalous counterintuitive response it was 1.043 mm (14.93%, Case C). Symmetry can thus be exploited as an active measurement principle to obtain quantitative blast-response data with substantially reduced experimental burden and without specialized stereo-optical instrumentation. Full article

This study investigates the dynamic interactions between Bitcoin, global financial indicators, and the Kazakhstan Stock Exchange (KASE) index within a VAR-based econometric framework, addressing a notable gap in the literature on emerging and shallow financial markets. While prior research predominantly focuses on developed economies, evidence suggests that cryptocurrency–stock market linkages are time-varying, crisis-sensitive, and often asymmetric. In this context, the present study examines both short-term causality structures and shock transmission mechanisms among KASE, Bitcoin (BTC), oil prices, the U.S. dollar index (DXY), and the VIX using monthly data for the period 2017M01–2026M04. Empirical findings indicate that, despite the absence of statistically significant Granger causality from individual global variables to KASE, the joint dynamics suggest a non-negligible, albeit indirect, interaction structure. Variance decomposition and impulse-response analyses further reveal that KASE dynamics are predominantly driven by its own shocks, reflecting the relatively segmented and internally driven nature of the market. Diagnostic tests confirm the robustness of the model, with no evidence of serial correlation or heteroskedasticity in residuals. These findings are consistent with the structural characteristics of the Kazakh financial system, including limited market depth, lower investor participation, and high sensitivity to domestic macroeconomic conditions. Unlike developed markets where stronger integration is observed, KASE appears only weakly connected to global financial and cryptocurrency markets. The study contributes to the literature by providing empirical evidence from a frontier market and highlights the importance of considering country-specific structural factors when evaluating financial integration. Policy implications emphasize the need to enhance market depth, transparency, and investor confidence to strengthen the responsiveness of KASE to global financial developments. Full article

Rolling element bearing degradation monitoring is critical for predictive maintenance in rotating machinery systems. Existing methods predominantly address fault classification and remaining useful life (RUL) estimation as separate tasks, thereby failing to capture the progressive and multistage nature of bearing deterioration. This paper proposes a physics-aware multi-modal fusion framework for continuous RUL prediction from vibration signals, organized around a stage-aware representation of the bearing life cycle. The proposed pipeline integrates two complementary preprocessing branches: Hilbert envelope demodulation followed by short-time Fourier transform (STFT) to generate degradation-sensitive time–frequency spectrograms, and handcrafted statistical feature extraction to yield compact global severity descriptors. A dual-head convolutional neural network-multilayer perceptron (CNN-MLP) architecture is designed to learn discriminative representations from both modalities and fuse them for end-to-end normalized RUL regression. The bearing life cycle is further partitioned into four ordered degradation stages based on normalized life–progress ratios, providing an interpretable health representation that complements the continuous prognosis target. Experiments conducted on the PRONOSTIA/FEMTO-ST benchmark dataset demonstrate that the proposed framework achieves an RMSE of 0.1597, an MAE of 0.1328, and an $R^2$ of 0.7487 on normalized RUL prediction, with stable error behavior across most of the life cycle. Feature importance analysis confirms that the CNN branch captures localized low-to-mid-frequency spectral evolution while the MLP branch encodes amplitude variability and impulsive indicators, validating the complementarity of the dual-branch design. The proposed method offers a unified, interpretable, and engineering-relevant solution for intelligent bearing condition monitoring and prognostic health management. Full article

This study investigated whether body-weight semi-squats (BWSSs) performed under blood-flow restriction (BFR) conditions were associated with higher post-conditioning drop-jump performance compared with the sham condition in adolescent female volleyball players. Thirteen players completed two experimental conditions (BFR and sham) in a randomized, counterbalanced crossover design. A pre-conditioning baseline jump assessment was not included. The BFR condition consisted of three sets of 16 repetitions with 80% of arterial occlusion pressure (AOP), whereas the sham condition was performed at 20% AOP. In each condition, participants performed one drop jump at 3, 6, 9, 12 and 15 min after the activation protocol. Jump height, impulse, reactive strength index (RSI) and power-related variables were analyzed using repeated-measures ANOVA. A significant main effect of condition indicated that jump height, RSI, impulse, and power-related variables were greater following the BFR than the sham condition across the post-conditioning assessment period. A significant main effect of time was also observed, with lower performance at 3 min compared to later time points. No condition-by-time interaction was found. These preliminary findings suggest that BWSSs performed under BFR conditions were associated with higher post-conditioning drop-jump performance than the sham condition. Low-load BFR exercise may therefore represent a practical strategy when heavy resistance equipment is unavailable. However, because no pre-conditioning baseline assessment was included, the magnitude of performance enhancement from baseline cannot be determined. Therefore, the findings should be interpreted as differences in post-conditioning performance between BFR and sham conditions rather than definite evidence of baseline to post enhancement. Full article

This paper investigates the interaction and price discovery mechanisms among the day-ahead, intraday, and balancing segments of the Greek wholesale electricity market under the European Target Model, emphasizing their contribution to a sustainable and flexible energy transition. Using a Vector Error Correction Model with exogenous variables (VECMX), hourly data from 2023 to September 2025 are analyzed, incorporating key system fundamentals and regime-dependent dynamics. The results reveal a hierarchical market structure in which the day-ahead market dominates long-run price discovery, the intraday market acts as a short-run adjustment mechanism, and the balancing market reflects real-time system conditions associated with renewable energy variability and system reliability. Forecast Error Variance Decomposition shows that day-ahead shocks explain most long-run price variation, while balancing market effects are mainly transitory. Cointegration analysis confirms stable long-run relationships among market segments, with imbalance prices anchored to forward market outcomes and moderated by intraday adjustments. Robustness tests based on alternative recursive orderings and Generalized Impulse Response Functions (GIRFs) confirm the stability of the results and the dominant role of the day-ahead market in price discovery. The findings have important policy implications for market design and sustainability, highlighting the role of integrated day-ahead, intraday, and balancing markets in supporting renewable energy integration, system flexibility, and the transition toward a resilient low-carbon electricity system. The Greek electricity market is gradually evolving toward a mature and resilient Target Model structure capable of supporting higher renewable energy penetration, improved operational flexibility, and enhanced market efficiency within the European decarbonization framework. Full article

Background/Objectives: Borderline personality disorder (BPD) is a severe mental disorder characterised by emotion dysregulation, impulsivity and interpersonal hypersensitivity. Its prevalence ranges from 0.5% to 6.4%. Eye tracking and pupillometry provide objective indices of social attention and inhibitory control, but the BPD literature using these techniques has not been systematically reviewed. The aim of this work was to synthesise the empirical evidence on visuo-attentional and pupillary alterations in BPD. Methods: Following the PRISMA 2020 statement, Web of Science, Scopus and PubMed were searched up to 13 March 2026, with no date or language restrictions. Search terms combined borderline personality disorder and eye-tracking constructs. Two reviewers independently screened records with complete inter-rater agreement at the title-and-abstract stage (Cohen’s κ = 1.00); two generative artificial-intelligence assistants (ChatGPT, NotebookLM) were additionally consulted as a non-systematic plausibility check and returned no eligible studies beyond the database search. Risk of bias was appraised with the framework appropriate to each study design (RoB 2 for randomised trials and Newcastle–Ottawa Scale logic for observational studies, with ROBINS-I held in reserve for non-randomised intervention designs). Results: Seventeen studies met the inclusion criteria, with sample sizes ranging from 19 to 164 participants and predominantly adult female samples. Designs included antisaccade and oculomotor tasks, free-viewing, dot-probe, affective priming and pharmacological challenge. Four findings recurred across studies. First, patients with BPD showed an early reflexive vigilance to the eye region of emotional and neutral faces, followed by reduced time on positive stimuli during longer presentations. Second, self-reported impulsivity was elevated, but laboratory inhibition was largely preserved; the deficits that did emerge were limited to preparatory control and were greater in patients with comorbid ADHD or under induced negative affect. Third, autonomic dysregulation was indexed by lower heart-rate variability and a larger baseline pupil size; in a single longitudinal study, pupillary reactivity was prospectively associated with subsequent symptom change. Finally, intranasal oxytocin reduced amygdala-driven vigilance. Conclusions: Eye-tracking and pupillometric measures appear to capture meaningful aspects of the BPD clinical picture. The two-stage profile of early vigilance followed by reduced sustained engagement is most parsimoniously described as a vigilance–avoidance pattern, which is compatible with, but not uniquely explained by, the hypersensitivity hypothesis of emotion dysregulation. Because thirteen of the seventeen studies recruited women only, these conclusions apply primarily to adult women with BPD. Methodological heterogeneity, the predominance of female samples and the scarcity of longitudinal data justify the need for standardised protocols, transdiagnostic comparisons and the inclusion of male and gender-diverse populations in future research. Full article

Graphite nozzles remain the dominant choice for small hybrid and solid rocket motors operating on laboratory and university budgets, owing to their low cost, ease of machining, and rapid turnaround during iterative design campaigns. These same programs, however, must contend with the fact that graphite erodes through coupled thermochemical and mechanical mechanisms when exposed to the oxidizing species generated by high-energy propellant combustion, and the resulting throat-area growth fundamentally alters the time histories of chamber pressure, thrust, and delivered specific impulse. This paper presents a nozzle-erosion reconstruction model that extracts the time-resolved throat area from coupled thrust and chamber-pressure measurements using the thrust coefficient relationship, scales the reconstructed area history against pre- and post-test throat measurements, identifies the onset and rate of erosion, and accounts for variable sensor lag between the thrust-stand and pressure-transducer signal chains. The model is exercised on two complementary sets of laboratory-scale GOX/ABS hybrid hot-fire data that together span roughly two orders of magnitude in total throat-area change and peak chamber pressures from 0.5 to 3.4 MPa: a controlled three-operating-point campaign conducted in support of the NASA Plume-Surface Interaction (PSI) program, and a set of higher-pressure firings from the laboratory development series in which the technique was matured. Reconstructed erosion-onset times, erosion rates, and total throat-diameter change are reported for each firing, the reconstruction accuracy is characterized as a function of erosion magnitude. A correlation of graphite erosion with chamber pressure is examined across the combined envelope. The results demonstrate the robustness of the reconstruction technique and provide a reusable framework for post-test reconstruction of transient nozzle geometry in rocket-engine ground testing. Full article

Countermovement jump (CMJ) analysis is widely used to assess lower limb neuromuscular function, but commercial force plates often suffer from high cost, closed algorithms, and lack of bilateral independent measurement. This study developed and evaluated a dual channel strain gauge force plate system featuring open architecture and hardware-triggered video synchronization. The system consists of two physically isolated plates, each with four full bridge strain beams, a precision analog front end, and a 2000 Hz acquisition unit. A microcontroller-based hardware trigger synchronizes force data with video capture. Custom host software implements adaptive jump phase recognition and calculates peak force (PF), concentric impulse, jump height, rate of force development (RFD), and asymmetry index (ASI). Validation included static mass measurements in 14 participants, low-load static calibration (5.0–30.0 kg), free-fall impulse validation (7.00 to 31.32 N·s), 240 fps high-speed video cross validation of flight time, ecological-validity comparison with published AMTI-based force-plate data, and 48 h test–retest reliability assessment. Static mass measurement showed a mean absolute percentage error (MAPE) of 1.01% and a coefficient of determination (${\mathrm{R}}^2$) of 0.9992, while low-load testing confirmed excellent linearity (${\mathrm{R}}^2>0.996$) and minimal absolute error (mean absolute error = 0.34 kg) at lighter weights. Dynamic impulse validation yielded ${\mathrm{R}}^2>0.997$ and MAPE < 3%. Flight time agreement with high-speed video was within ±10 ms. Test–retest reliability was excellent for concentric impulse (intraclass correlation coefficient (ICC) = 0.997) and jump height (ICC = 0.987), and good for PF (ICC = 0.962) and rate of force development at 100 ms (RFD_100ms) (ICC = 0.883). The physically isolated dual-plate architecture effectively captured bilateral force differences, although the ASI demonstrated moderate reliability (ICC = 0.748), likely reflecting the inherent biological variability in bilateral coordination. The ecological-validity comparison further indicated that the macroscopic kinetic outputs of the proposed system fell within the expected physiological and biomechanical ranges reported for adult CMJ testing. Overall, these findings support the study hypothesis that the proposed dual-channel force plate system provides a valid, reliable, and cost-effective solution for synchronized bilateral CMJ kinetic assessment in sports performance monitoring and biomechanical research, while offering improved accessibility through an open-source and transparent analysis framework with a hardware cost below 500 USD. Full article

Background: The relationship between force–time characteristics and bilateral symmetry in striking techniques remains unclear, particularly whether these variables reflect partially separable descriptors or a broader coordinated force–time organization. The aim of this study is to examine bilateral symmetry and force–time characteristics in the sonkal taerigi technique, and to determine whether these variables exhibit a dominant multivariate organization with an additional force-application-related dimension. Methods: Fifteen experienced male taekwon-do practitioners performed knife-hand strikes under controlled laboratory conditions, including outward and inward variants performed with both dominant and non-dominant limbs. Force–time variables, including rate of force development (RFD), contact time, impulse, peak force, and relative force, were calculated from ground reaction force data. Bilateral symmetry was assessed using the symmetry index. Principal Component Analysis (PCA) and k-means clustering were applied as exploratory multivariate approaches. Results: Asymmetry was generally low and direction-dependent, with higher values observed in outward strikes. PCA revealed a dominant first component representing shared variance among force–time variables (RFD: 0.78; contact time: 0.74; impulse: 0.92; peak force: 0.81) and a secondary component reflecting variation between rapid force production and longer force application. Clustering identified three graded profiles distributed along a continuous multivariate distribution. Conclusions: Force–time characteristics appeared to be primarily organized along a dominant multivariate pattern with an additional force-application-related dimension, while symmetry remained embedded within the same general organization. Full article

In past decades, the macroeconomic stability of India has been tested repeatedly by major global disruptions, including oil price shocks, the 2008 global financial crisis and the COVID-19 pandemic. Analysing how macroeconomic variables respond to these shocks is essential for evaluating external vulnerability and policy resilience in emerging economies. Our study provides a comprehensive empirical investigation of the dynamic responses of wholesale price inflation, industrial output, oil prices and exchange rates in India by employing monthly data from January 1993 to December 2024. To examine long-run equilibrium relationships along with short-run adjustment dynamics, the present study employs co-integration analysis within a Vector Error Correction Model (VECM) framework. Further, we applied impulse response functions and forecast error variance decomposition to track volatility spillover mechanisms. Quantile regression and ARCH–GARCH models were further estimated to account for distributional heterogeneity and time-varying volatility. The findings of our study suggested stable long-run linkages among the selected variables, where oil price shocks emerged as a key external source of macroeconomic fluctuations. Short-run dynamics suggested that shocks in oil prices are transmitted primarily through inflation and exchange rate channels and then affect industrial output. Distributional estimates revealed the effects were stronger during stress periods, indicating tail risks that were not captured by the mean-based models. Lastly, volatility analysis confirmed persistent clustering, especially during phases of crisis. Overall, the findings suggest that India’s macroeconomic system remains externally sensitive, with adjustment mechanisms that operate gradually but come under strain during global disruptions. These results underscore the importance of energy risk management and crisis-responsive macroeconomic stabilisation policies. Full article

Understanding how geometry, surface condition, and polarity influence surface flashover is important for improving the reliability of polymeric insulation in high-voltage systems exposed to transient overvoltages. The purpose of this study was to experimentally investigate visible arc path behaviour on polymeric insulators made of polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), and nylon under standard 1.2/50 µs lightning voltage impulses. Cylindrical, concave, and convex profiles were tested in a rod–plane configuration for both positive and negative polarities under clean and sunflower oil- coated surface conditions. Seven arc types were observed. While the visible arc path was governed mainly by geometry and polarity, the electrical breakdown response exhibited material-dependent effects. Positive-polarity oil-coated samples generally exhibited longer time-to-breakdown, while negative-polarity tests produced higher breakdown voltages, and oil often reduced the withstand level. The large variability in time-to-breakdown data indicates that impulse flashover is strongly stochastic and sensitive to small surface or field variations. The findings highlight the need for improving control of surface films, expanding environmental testing, and conducting further modelling to predict flashover behaviour across different insulator designs. Full article

Vertical ground reaction force is an important parameter for describing the developmental characteristics of young children’s vertical jumping. However, its application in large-scale physical fitness monitoring and routine teaching practice is greatly limited. Previous studies have used OpenCap to estimate vertical ground reaction force during adult jumping tasks and have provided preliminary validation, but its effectiveness in young children remains unclear. To examine the correlation and agreement of vertical ground reaction force (GRF) estimated by the OpenCap markerless motion capture system during young children’s vertical jumping and to explore the characteristics of vertical GRF estimated by OpenCap during the vertical jump. Kinematic and kinetic data during vertical jumping were synchronously collected from 16 young children using the OpenCap markerless motion capture system and a three-dimensional force platform, with each child completing three trials. Kinematic data were acquired using the OpenCap markerless motion capture system, and the vertical acceleration of the whole-body center of mass was calculated to estimate vertical GRF based on Newton’s second law. Pearson linear correlation analysis and Bland–Altman analysis were used to examine the differences in characteristics between the estimated vertical GRF and the measured vertical GRF. The vertical GRF characteristics estimated by OpenCap showed moderate-to-high correlations with the measured values. Specifically, the time and mean impulse during the push-off phase, flight phase, and landing stabilization phase were highly correlated (r > 0.85), while the peak force and mean force during the push-off phase showed moderate-to-high correlations (r > 0.7). Bland–Altman analysis showed that the bias in time and impulse during the vertical jump was less than 15%, indicating relatively high agreement; however, the bias in peak force during the landing phase exceeded 40%, indicating weak agreement. These results suggest that the OpenCap markerless motion capture system can effectively estimate vertical GRF characteristics during young children’s vertical jumping, with the best performance observed for vertical GRF variables in the push-off phase. The method used in this study may be applied to obtain vertical GRF during young children’s vertical jumping in non-laboratory settings and to assist in evaluating the developmental level of young children’s vertical jump performance. Nevertheless, OpenCap-derived rapid impact variables, particularly landing peak force, should be interpreted with caution. Full article

Post-traumatic auditory and vestibular complaints are frequent after traumatic brain injury (TBI) and temporal bone trauma. They create particular difficulty in medico-legal practice because the evaluator must distinguish diagnosis, functional impact, plausibility of traumatic causation, and the credibility of reported deficits and/or symptoms. This manuscript is a narrative expert review, not a systematic review or a validated forensic prediction rule. It aims to synthesize clinically relevant evidence and propose a practical cross-check framework for structured audio-vestibular assessment in post-traumatic and medico-legal contexts. Pure-tone audiometry remains the functional entry point, but it should be interpreted in conjunction with speech audiometry, tympanometry, acoustic reflexes, transient-evoked and distortion-product otoacoustic emissions, auditory brainstem responses, and auditory steady-state responses. Vestibular evaluation should combine videonystagmography, video head impulse testing, cervical and ocular vestibular evoked myogenic potentials, and computerized dynamic posturography, recognizing that each method interrogates different physiological domains and frequencies. Particular emphasis is placed on the separation between clinical diagnosis, physiological localization, functional impairment, and medico-legal attribution. The article also discusses safeguards against false-positive attribution of malingering, the time course after TBI, inter-rater variability, and the role of specialist expertise in medico-legal reporting. The proposed framework does not eliminate uncertainty; rather, it is intended to make expert reasoning transparent, cautious, internally consistent, and defensible. Full article

Background: The effectiveness of striking techniques in combat sports depends not only on peak force but also on how force is applied over time. The knife-hand strike (sonkal taerigi) in ITF taekwon-do can be executed in inward and outward directions; however, biomechanical differences between these variants and the role of limb laterality remain unclear. This study aimed to evaluate the effects of movement direction and limb side on selected kinetic variables. Methods: Fifteen experienced male taekwon-do practitioners (black belts, ≥10 years of training) performed knife-hand strikes using both hands (right and left) and two movement directions (inward and outward) on a ground reaction force platform. Three trials were recorded for each condition. The analyzed variables included peak resultant force (F), relative force (Fr), contact time (t), and impulse (J). Paired t-tests or Wilcoxon signed-rank tests were applied depending on data distribution, and effect sizes were calculated. Results: Inward strikes produced significantly higher resultant force (F), relative force (Fr), impulse (J), and slightly longer contact time (t) compared to outward strikes (all p ≤ 0.001), with large to very large effect sizes. The effect of limb side was limited and statistically significant only for impulse (p = 0.031), indicating generally high bilateral symmetry. Differences in contact time, although significant, were of negligible practical magnitude. Conclusions: Movement direction is the primary determinant of biomechanical effectiveness in the sonkal taerigi technique. Inward strikes provide more favorable mechanical conditions for force and impulse generation, whereas the influence of limb laterality is minimal. Impulse appears to be a sensitive and functionally relevant indicator of striking performance and may be particularly useful for performance assessment and training monitoring. Full article

The decoupling of physical loading configurations from dynamic temperature control in cold-chain logistics exposes supply chains to severe thermal compliance risks and exponential cost penalties. To address this structural gap, this study formulated the Cold Chain Unitization Loading Optimization Problem (CCULP). We propose a mixed-integer linear programming (MILP) model that integrates continuous-time heat-transfer dynamics—including door-opening impulse disturbances—and Q10-driven quality-decay kinetics as endogenous constraints within the hierarchical assignment of perishable goods to insulated containers, pallets, and vehicles. By treating container thermal resistance as a core decision variable, the model operationalizes a “prevention-first” economic strategy. To solve this NP-hard problem, we developed a Temperature-Aware Heuristic Algorithm (TAHA) that embeds a forward-Euler temperature simulation loop directly into the combinatorial search. Computational experiments on instances up to 100 SKU types demonstrate that TAHA achieves near-optimal solutions (within 0.7% of the MILP proven optimum) while converging 63 times faster than a genetic algorithm benchmark. Moreover, compared with traditional geometry-centric heuristics, TAHA’s proactive container-polarization strategy effectively eliminates the “penalty cliff,” yielding up to a 25.9% reduction in total system cost on Large-scale instances, almost entirely attributable to the elimination of temperature-violation penalties. Sensitivity analyses further confirm TAHA’s robustness under extreme environmental stress (e.g., 40 °C ambient temperatures) and frequent logistical disturbances, offering an integrated framework for proactive risk mitigation and for reducing food loss in sustainable temperature-controlled distribution. Full article