Search Results (227)

The availability of critical spare parts is essential for maintaining the reliability and operational continuity of combined cycle power plants. However, demand for critical spare parts is typically sparse, intermittent, and highly non-linear, which limits the effectiveness of conventional forecasting approaches based on historical averages or expert judgment. Inaccurate demand estimation may lead to excessive inventory, high holding costs, or stock shortages that increase downtime risks. To address these challenges, this study applies ensemble learning methods to improve demand forecasting accuracy for critical spare parts in a combined cycle power plant. Procurement and usage data from 2020 to 2024 were analyzed using a time-series splitting approach, with model performance assessed using Root Mean Squared Error (RMSE), Mean Absolute Error (MAE), and Mean Absolute Percentage Error (MAPE). To avoid bias caused by zero-demand periods, zero actual values were excluded from MAPE calculations. The results show that the tuned XGBoost model consistently performs better than Random Forest by producing lower forecasting errors and more stable predictions under intermittent demand conditions. These findings indicate that ensemble learning can support more effective procurement planning, inventory control, and maintenance decision-making in combined cycle power plant operations. Full article

Inland water management is increasingly important under climate change due to the need for landscape-scale water retention, but in situ studies are limited by fluctuating, shallow, and intermittent water cover. This study simulated prolonged waterlogging under controlled laboratory conditions. Four agricultural soils (Calcisol, Arenosol, Chernozem, and Solonetz) were flooded for 40 days using identical 1:5 soil-to-water ratios at two temperature regimes, at 4 and 22 °C. Given that periodic water cover may conflict with agricultural production, particular attention was paid to crop-relevant indicators, including pH, water-soluble salts, and N, P, K. The laboratory simulation revealed significant differences among soil types and between temperature treatments. Elevated Mg concentrations limited the irrigation suitability of leachate derived from Calcisol, with Mg% values ranging from 57 to 64%, exceeding the 50% guideline threshold. Soil buffering capacity controlled phosphorus and potassium dynamics, resulting in stable or slightly increasing AL-soluble nutrient levels, except in low-buffering sandy soils where up to 3–4-fold variability was observed. Reductive conditions developed early in the Calcisol samples, supported by dissolved oxygen saturation values below 20% during the first days of the experiment. Oxygen saturation increased later, only exceeding 60% twice in the cooled Calcisol treatment, while nitrate–ammonium dynamics reflected changing redox conditions. Temperature significantly affected solubility and nutrient mobility, partly through its influence on microbial activity. These findings improve our understanding of inland water–soil interactions and support the development of sustainable, water-retentive land management strategies. Full article

This study explores a photovoltaic/thermal (PV/T)-based electrolysis system designed for dual production of hydrogen fuel and domestic hot water (DHW), providing a sustainable energy solution amid rising global emissions. A dynamic rule-based control mechanism with hysteresis thresholds on hydrogen-storage state of charge (SoC) is implemented to balance electrolyzer operation with intermittent solar availability, maintaining PV/T power outputs while preventing storage overfilling and minimizing start–stop cycling. The system is assessed across 27 geographically diverse cities spanning a wide range of solar irradiation and energy price structures. Annual hydrogen yields range from 20 kg/yr in high-latitude locations (Helsinki, Stockholm) to 33.5 kg/yr in high-irradiation regions (Riyadh, Abu Dhabi), while the levelized cost of hydrogen (LCOH) spans from 6.47 USD/kg (Riyadh) to 22.86 USD/kg (Helsinki). Economically, the system achieves its strongest performance in solar-rich, high-energy-cost environments: Rome records the highest net annual cash flow (858.9 USD/yr) and shortest payback period (2.47 years), followed by Davos, Madrid, Brasília, and Canberra. In contrast, locations with subsidized energy tariffs—such as Algiers, Kyiv, and Tehran—yield low or negative net cash flows, rendering the system economically unviable without policy support. Environmental analysis reveals annual CO₂ avoidance ranging from 0.33 ton/yr (Stockholm) to 2.97 ton/yr (Riyadh), with a global mean of 1.095 ton/yr and a combined total of approximately 29.6 tons/yr across all examined sites. A machine learning model is developed to generalize performance predictions across unseen locations, achieving leave-one-out (LOO) R² values of 0.953 (net cash flow), 0.935 (LCOH), and 0.947 (LCO-DHW), with mean absolute errors below ±1 USD/kg and ±0.03 USD/kWh. The findings confirm that, under fixed capital cost assumptions, local electricity price and solar irradiation are the dominant drivers of economic viability, while grid carbon intensity and solar resource jointly govern environmental performance, with markets offering irradiation above 1500 kWh/m²·yr and electricity prices exceeding 0.2 USD/kWh representing the most promising deployment targets. Full article

Background: Blood flow restriction (BFR) resistance exercise has emerged as a training methodology capable of inducing muscular adaptations comparable to traditional high-load training despite substantially lower mechanical loads. While low-load BFR protocols (20–50% 1RM) are well-established, emerging evidence supports applications across the full loading spectrum, including moderate-to-high loads (>50–90% 1RM), contralateral training effects, and proximal–distal adaptations. In this second installment of the Blood Flow Restriction in Athletic Populations series, we review current evidence on BFR resistance exercise in athletic populations, with emphasis on morphological, neuromuscular, and functional adaptations across diverse application contexts. Methods: A narrative review of research examining BFR resistance exercise in trained and athletic populations was conducted via a PubMed/MEDLINE search. Search terms: (“blood flow restriction” OR “BFR” OR “occlusion training” OR “KAATSU”) AND (“resistance training” OR “resistance exercise” OR “strength training”) AND (“athletes” OR “athletic” OR “trained” OR “elite” OR “sport”) AND (“cross-education” OR “contralateral” OR “cross transfer” OR “proximal” OR “distal”). Studies investigating low-load (20–50% 1RM) and moderate-to-high load (>50% 1RM) protocols, contralateral cross-education effects, and proximal–distal adaptations were evaluated. Primary outcomes included muscle hypertrophy, strength, power, and sport-specific performance measures. Results: Low-load BFR resistance exercise has been shown to produce significant improvements in muscle hypertrophy and strength gains over 4–12 week interventions compared to low-load control conditions. Moderate-to-high load BFR enhanced barbell velocity and power output, particularly at loads > 80% 1RM with intermittent inflation protocols. Contralateral and cross-transfer effects of BFR training demonstrate variable efficacy across muscle groups, with the most consistent evidence supporting cross-transfer enhancement of training adaptations when BFR is applied to one body region while exercising another. Proximal BFR application induced adaptations in both proximal and distal musculature, suggesting systemic mechanisms beyond local vascular restriction. Conclusions: BFR resistance exercise represents a versatile training modality producing meaningful morphological and neuromuscular adaptations across the loading spectrum. Contralateral and proximal–distal effects expand practical applications for injury rehabilitation and targeted adaptation. These findings support BFR integration within periodized training programs when mechanical load management is prioritized. Full article

Intermittently operated, tankless reverse osmosis (RO) systems are widely used in decentralized and point-of-use applications, yet water stagnation during idle periods remains a critical challenge, leading to degraded water quality, accelerated fouling, and performance loss. This study presents an experimentally validated engineering solution that eliminates stagnant water in intermittently operated RO systems. A dual-membrane RO configuration with flexible series–parallel switching was developed, enabling membranes to alternate between production and flushing modes. An adaptive control strategy, integrated into the system hardware, regulates membrane switching and flushing based on real-time feed-water quality. The proposed configuration and control framework was evaluated under representative intermittent operating conditions. Experimental results show that the zero-stagnant-water strategy effectively prevents residual water accumulation during shutdown and maintains stable permeate quality, with total dissolved solids consistently below 10 mg/L. Long-term testing further demonstrates reduced membrane fouling and slower performance degradation compared with conventional fixed-operation schemes, resulting in enhanced desalination efficiency and operational stability. Owing to its modular design and simple control logic, the proposed approach is readily transferable to decentralized and point-of-use membrane water treatment systems requiring reliable, high-quality water under intermittent operation. Full article

Epilepsy is associated with impaired reproductive function and testicular pathologies. Intermittent fasting (IF) is a nonpharmacological metabolic intervention with anti-inflammatory and antioxidant effects. This study investigated the protective effects of IF on testicular damage in a genetic absence epilepsy rat model (GAERS), focusing on histomorphology, oxidative stress parameters, and hormonal profiles. Testicular tissues from Wistar control (WC), Wistar + IF (WIF), GAERS control (GC), and GAERS + IF (GIF) groups (total n = 20; 5 rats per group) were evaluated using hematoxylin and eosin and Periodic Acid–Schiff staining. Apoptosis and spermatogenic cell integrity were assessed using caspase-3, P-element-induced wimpy testis (PIWI), and Deleted in Azoospermia-Like (DAZL) immunohistochemistry. Johnsen’s score, seminiferous tubule diameter, and epithelial thickness were quantified. Oxidative stress markers, including catalase, malondialdehyde, glutathione, myeloperoxidase, and superoxide dismutase, were measured using spectrophotometric methods, and serum testosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels were determined using ELISA kits. The GC group showed significantly reduced Johnsen scores, tubular diameters, and epithelial thickness, along with disrupted basement membrane integrity and increased caspase-3 immunoreactivity. IF significantly improved histological parameters, restored basement membrane integrity, reduced apoptosis, and increased PIWI and DAZL expression in the GIF group. IF also ameliorated oxidative stress and elevated reproductive hormone levels, indicating positive modulation of the hypothalamic–pituitary–gonadal axis. In conclusion, IF reduces oxidative stress and preserves seminiferous tubules and hormonal function in genetic absence epilepsy, highlighting its potential as a supportive nonpharmacological approach to protect male reproductive health. Full article

Background: In 2018, malaria remained a leading cause of morbidity and mortality in the Democratic Republic of the Congo, accounting for 44% of all outpatient visits and 22% of deaths. This led to the development of the strategic plan for 2020–2023. To meet the objectives of this renewed plan, a monitoring and evaluation program focusing on performance indicators was established. This study aimed to assess the malaria control performance indicators in Kinshasa. Methods: A descriptive cross-sectional study used the National Malaria Control Program dataset of the period 2020–2023 to analyze malaria data from 23 HZ (Health Zone) in Kinshasa. Diagnostic, therapeutic, and preventive use of LLINs (long-lasting insecticidal nets) and sulfadoxine–pyrimethamin-based IPT (intermittent preventive treatment among pregnant women) indicators were evaluated following the targeted thresholds established in the strategic plan for 2020–2023. Results: Malaria was present in all studied HZ from 2020 to 2023, with a heterogeneous distribution. The malaria incidence during the study period was 30%, with an upward trend in both suspected and confirmed cases, peaking in 2022 and showing no further fluctuations thereafter. The proportion of LLINs distributed to pregnant women during antenatal care visits was 62%, 61%, 45%, and 88% in 2020, 2021, 2022, and 2023, respectively. A total of 83.1% of suspected malaria cases were diagnosed using RDT (Rapid Diagnosis Test), and confirmed malaria cases received antimalarial treatment. Conclusions: The objectives of the 2020–2023 strategic plan were only partially achieved, and no HZ reached 100% diagnosis by RDT, with only four HZs reaching at least 95% of the target. Thirty-four HZs were able to benefit from 95% treatment with antimalarial drugs. 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

In this study, we employed forced convective cooling under the fan-cooling garment (FC condition) and conductive cooling under the neck cooling device (NC condition) in a hot environment during intermittent exercise to compare their effects on thermophysiological and subjective responses. Cooling was examined under two conditions: continuous application throughout both exercise and rest periods (Experiment 1) and application solely during rest periods (Experiment 2). As different participant groups were utilized for each experiment, the effects of cooling timing were interpreted in an exploratory manner. No differences were observed between conditions at baseline. In the FC condition, whole-body heat dissipation (HF_mean) significantly increased (p < 0.05), particularly during the recovery phase, and was associated with significant suppression of mean skin temperature rise (p < 0.05) and enhanced thermal comfort. Conversely, although localized heat dissipation at the neck (HF_neck) significantly increased under the NC condition, its effects on whole-body heat dissipation and mean skin temperature were limited. No consistent differences were observed between cooling conditions in axillary temperature or heart rate responses. These results suggest that forced convective cooling, which facilitates ventilation within clothing, and localized conductive cooling exhibit distinct thermal response characteristics. This study provides fundamental comparative data under controlled conditions, contributing to the understanding of the response characteristics of wearable cooling devices. Full article

Soccer is an intermittent sport that requires complex and well-adjusted physiological responses from athletes. The training load allows athletes to optimize physical adaptations and reduces the risk of musculoskeletal injuries. In women’s soccer, the implementation of load control and individualization strategies has shown promise for enhancing anaerobic performance and injury prevention. This study aimed to compare the performance levels of professional women’s soccer players before and after the implementation of relative external load (RELC) for training prescription. Twenty-seven female professional soccer athletes (mean age 29.4 ± 6.2 years) were evaluated. Metrics such as total distance, sprint distance, number of sprints, accelerations, and decelerations were collected using the GPS-based device Catapult One (Catapult). Athletes were assessed in two games, with 6 months’ difference between matches: Game 1, without RELC implementation, and Game 2, with RELC. Significant differences were found between both periods. Sprint distance increased from 391 m to 450 m (+15%, d = 0.49, p ≤ 0.05), and sprint count increased from 14 to 17 (+21%, d = 0.35, p ≤ 0.05), showing improved performance related to increased physical output in the second half of the season. These findings suggest potential performance improvements associated with individualized load control over the course of the season. Full article

The increasing penetration of intermittent renewable energy demands innovative solutions to maintain grid stability, resilience, and security in the body of smart cities. This paper presents a novel framework that redefines Bitcoin mining as a form of virtual energy storage, a flexible and controllable load capable of delivering large-scale demand response services, positioning it as a competitive alternative to traditional energy storage systems, including electrical, mechanical, thermal, chemical, and electrochemical storage solutions. By strategically aligning mining activities with grid conditions, Bitcoin mining can absorb excess electricity during periods of oversupply, converting it into digital assets, and reduce operations during times of scarcity, effectively emulating the behavior of conventional energy storage systems without the associated capital expenditures and material requirements. Beyond its operational flexibility, this paper explores the cyber–physical benefits of integrating Bitcoin mining into the power transmission systems as a defensive mechanism against false data injection (FDI) cyberattacks in smart city infrastructure. To achieve this goal, a decentralized and adaptive control strategy is proposed, in which mining loads dynamically adjust based on authenticated grid-state information, thereby improving system observability and hindering adversarial efforts to disrupt state estimation. In addition, to handle the proposed approach, this paper introduces a high-performance algorithm, a combination of quantum-augmented particle swarm optimization and wavelet-oriented whale optimization (QAPSO-WOWO). Simulation results confirm that strategic deployment of mining loads improves grid sustainability by utilizing curtailed renewables, enhances resilience by mitigating load-generation imbalances, and bolsters cybersecurity by reducing the impacts of FDI attacks. This work lays the foundation for a transdisciplinary paradigm shift, positioning Bitcoin mining not as a passive energy consumer but as an active participant in securing and stabilizing the future power grid in smart cities. Full article

Background/Objectives: Autism is a complex neurodevelopmental condition characterized by social and cognitive impairments, with growing evidence implicating neuroinflammation, disrupted autophagy, apoptosis, GABAergic dysfunction, and gut permeability in its pathophysiology. Thus, this study aimed to evaluate the independent and combined effects of intermittent fasting (IF) and the next-generation probiotic Akkermansia muciniphila on behavioral outcomes and molecular markers in prenatal valproic acid (VPA)-induced autism model. Methods: Male rat offspring were allocated into five groups (n = 8 per group): control, VPA, IF, probiotic, and IF + probiotic. The groups other than the control group were exposed to 500 mg/kg VPA prenatally to establish an autism model. Intermittent fasting (16:8 time-restricted feeding) and Akkermansia muciniphila (1 × 10⁹ cfu/day) were applied for 30 days. Behavioral tests (stereotypy, social interaction, memory, and anhedonia) were performed during the last eight days of the treatment period, and the rats were sacrificed the following day for collection of brain tissue and serum samples. Proinflammatory, apoptotic, autophagic, and GABAergic markers were measured in the prefrontal cortex and hippocampus, while zonulin levels were measured in the serum. Data were analyzed using one-way ANOVA followed by Tukey’s post-hoc test. Results: Prenatal VPA exposure worsened all behavioral and molecular parameters. All treatments improved stereotypy, social interaction, and memory, whereas anhedonia improved only in the combined treatment group. The treatments also decreased neuroinflammation and apoptosis-related imbalance while enhancing autophagy and GABAergic markers. In terms of apoptosis- and autophagy-related markers, the IF-only and probiotic-only treatments were effective in the prefrontal cortex, while the IF + probiotic treatment showed its effect in both brain regions. Lastly, all treatments were successful in alleviating elevated serum zonulin levels. Conclusions: Intermittent fasting and Akkermansia muciniphila alleviate VPA-induced behavioral and neurobiological impairments. The combined treatment, in particular, offers stronger and multi-targeted therapeutic potential. Full article

Although many countries have reduced the use of agricultural price intervention policies, such measures continue to be applied intermittently by the Thai government. In the current work, which examines the cassava price intervention policy from 1981 to 2024 in Thailand through a supply and demand framework, the authors estimate a dynamic simultaneous equation model (DSEM) via the lag-augmented three-stage least squares (LA-3SLS) approach in order to measure the welfare effects of these interventions. The results indicate that the policy mainly redistributes welfare among market participants rather than improving allocative efficiency. Producers experience temporary income gains during intervention periods, but these gains dissipate once the policy is withdrawn, leaving long-run total surplus largely unchanged. When fiscal costs are incorporated, the intervention generates a net welfare loss, suggesting limited contribution to long-term economic sustainability. The findings suggest that policy approaches emphasizing income stabilization and productivity enhancement are more consistent with long-term welfare and fiscal sustainability than reliance on direct price controls, with direct relevance to SDG 1 (No poverty) and SDG 8 (Decent work and economic growth), highlighting trade-offs between income support, market efficiency, and fiscal sustainability in agricultural policy design. This study contributes by integrating a welfare-based dynamic econometric framework with sustainability assessment, which enables long-term welfare metrics for evaluating the economic sustainability of agricultural price policies. Full article

Indoor air quality (IAQ) in healthcare facilities is increasingly recognized as a key determinant of occupant health, comfort, and operational performance. Owing to heterogeneous space functions, varying occupancy patterns, and dynamic operational conditions, IAQ parameters may exhibit marked spatial and temporal variability within the same facility. University-affiliated healthcare buildings, where clinical services coexist with academic and administrative activities, represent particularly complex indoor environments that remain relatively underexplored in the current IAQ literature. This study examines the spatiotemporal variability of indoor carbon dioxide (CO₂) and fine particulate matter (PM_2.5) concentrations across four representative functional zones within a university-affiliated healthcare facility, including a patient waiting room, an academic office, an administrative office, and a restorative dental clinic. Continuous, long-term monitoring was conducted over a multi-month period to capture both spatial differences and diurnal dynamics under real operational conditions. Daily mean CO₂ concentrations varied across functional zones, ranging from approximately 540 to 620 ppm, with higher levels generally observed in spaces with sustained occupancy and limited ventilation. Daily mean PM_2.5 concentrations ranged from approximately 13 to 18 µg/m³, with greater variability detected in zones associated with intermittent activities and procedural sources. Unlike many IAQ studies focusing on single departments or short-term campaigns, this multi-zone, long-term assessment within a shared building infrastructure enables direct comparison of functional spaces and identification of time-specific exposure patterns. Overall, the findings highlight that IAQ conditions within healthcare facilities are shaped by both space function and temporal factors, even under shared ventilation infrastructure. The results emphasize the value of zone-specific and time-resolved IAQ assessment approaches and provide evidence-based insights to support targeted ventilation strategies, activity-aware operational controls, and improved indoor environmental management in healthcare settings. Full article

Solar-driven hydrogen production is a cornerstone of sustainable energy systems, yet its implementation remains intrinsically constrained by reliance on continuous illumination, limiting temporal control and compatibility with intermittent renewable sources. This perspective articulates the emerging concept of on-demand solar hydrogen generation, in which photon absorption is intentionally decoupled from hydrogen evolution through reversible charge storage and stimuli-responsive catalytic activation. We introduce a systematic classification of on-demand approaches across molecular, semiconductor, and device-level platforms, highlighting how these architectures enable programmable hydrogen release triggered by electrical, chemical, or thermal stimuli and sustained operation beyond illumination periods. Moving beyond a descriptive survey, we propose key performance metrics, including Switching Efficiency, Response Time, and Cycle Fidelity, to enable consistent evaluation and comparison of on-demand systems. Recent advances demonstrate substantial progress in charge storage, catalytic reversibility, and dynamic control, directly addressing the intermittency limitations of conventional photocatalytic and photoelectrochemical technologies. While challenges remain in kinetic synchronization, durability, and scalability, on-demand hydrogen concepts establish a coherent design framework for flexible and dispatchable solar fuels. By enabling integration with variable renewable inputs, this paradigm points toward adaptive and intelligent solar-fuel systems applicable from grid stabilization to off-grid and extraterrestrial environments. Full article