Search Results (54,671)

Hydrogen is a key energy carrier for the transition to renewable energy, but its storage remains a major challenge, mainly due to the energy requirements for its production and to its low volumetric energy density under ambient conditions. Clathrate hydrates have recently emerged as a promising medium for gas storage, yet their potential for hydrogen storage is still underexplored. This study presents a comprehensive bibliometric analysis of hydrogen storage research, focusing on clathrate hydrates. The analysis, based on publications indexed in Scopus over the past decades, reveals that research on gas hydrates is mature and interdisciplinary, encompassing hydrate formation, thermodynamics, and production from natural reservoirs. In contrast, hydrogen hydrates remain a marginal and emerging research area, characterized by limited scientific output and weak connections to dominant storage strategies such as metal hydrides, metal–organic frameworks, and adsorptive materials. The results highlight key research gaps, including a limited understanding of formation kinetics, thermodynamic stability under practical conditions, and challenges related to scalability and system integration. These findings suggest that targeted research efforts addressing these bottlenecks could support the development of hydrate-based systems as complementary solutions within the broader hydrogen storage landscape. Full article

As mining operations progressively advance to greater depths to meet increasing mineral demand, there is a growing need to develop new or improved rockbolts capable of effectively dissipating energy under dynamic loading conditions. Impact laboratory tests provide valuable insights into the dynamic performance of rockbolts; however, such tests require considerable time and cost associated with specimen preparation and experimental validation. Numerical modeling represents a robust alternative which, when properly calibrated with laboratory results, can accurately simulate the deformation process and energy dissipation mechanisms of support elements. This paper presents the implementation and results of a numerical model developed to simulate the dynamic behavior of a threadbar subjected to impact loading. The model explicitly represents all components of a full-scale impact test configuration, including the impact mass, reaction frame, threadbar geometry, grout, and steel tube. The numerical model enables real-time analysis of the dynamic response and interaction among the test components (steel tube, grout, and bolt). The implemented numerical codes were calibrated and validated against published laboratory results of threadbar dynamic behavior. Subsequently, a comprehensive parametric analysis was conducted to evaluate the response of each component in terms of load, displacement, and dissipated energy. The results allowed identification of the primary factors governing the dynamic response of the rockbolt system. The proposed methodology can be extended to other reinforcement systems and provides relevant insights into the design of bolts under dynamic loading conditions. Full article

Driven by global carbon reduction targets, supersulfated cement has emerged as a promising low-carbon cementitious material. This study investigates the influence of a polycarboxylate superplasticizer (PCE) on the rheological behavior and early interfacial evolution of phosphogypsum-based supersulfated cement (PSSC). Rheological measurements, pore solution ion analysis, hydration heat analysis, X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS) are employed to correlate early hydration processes with structural development. The results indicate that the incorporation of PCE significantly reduces the initial yield stress and moderates the structural build-up rate. At a PCE dosage of 0.3 wt.%, the initial static yield stress decreases from 1313 Pa to approximately 125 Pa, while the structural build-up index I_s,s reaches 10.19, indicating improved particle dispersion while maintaining progressive structural reconstruction during hydration. Phosphogypsum (PG) functions not only as a sulfate source but also as an active interfacial substrate that promotes the preferential nucleation of AFt on its surface. In the absence of PCE, continuous Ca–P-enriched layers form on PG particles, accompanied by localized AFt accumulation. After the incorporation of PCE, the primary crystalline phases remain unchanged; however, gypsum dissolution and AFt formation are delayed. Meanwhile, Ca–P enrichment shifts from continuous coverage to a more dispersed distribution, promoting the spatially separated growth of AFt crystals rather than dense localized aggregation. Overall, PCE influences the evolution of the structure and properties of the system by regulating early interfacial reactions and the spatial organization of hydration products. Full article

Fretting wear significantly limits the service life of metal O-rings operating under harsh conditions. To address this limitation, this study investigates the wear behavior of metal O-rings under equivalent accelerated reciprocating motion and establishes an accelerated life prediction model based on similarity theory. Fretting wear experiments were conducted using Inconel 718 alloy and 304 stainless steel to replicate service conditions in a controlled laboratory environment. Wear morphology was characterized using laser scanning confocal microscopy, revealing a progressive transition from mild abrasive and adhesive wear to severe abrasive wear accompanied by material spalling. Based on the experimental results, regression analysis was performed to estimate the acceleration model coefficients, leading to the formulation of an equivalent acceleration equation capable of predicting seal wear life under practical service conditions. The resulting equivalent acceleration model can establish a quantitative connection between the acceleration test and the operating conditions. This model can shorten the testing time and can be used to predict parameters related to the surface morphology of static seals, providing a theoretical and experimental basis for reliable life assessment. This provides a practical basis for improving the reliability and safe operation of metal O-ring seals in critical applications, including nuclear energy and chemical processing systems. Full article

The biomechanics of frog jumping has been a subject of significant interest in both biology and engineering, driven by the high efficiency of their movement. This study presents the dynamic simulation of a frog’s complete jump cycle, from take-off to landing and re-stabilization, to advance the development of bio-inspired jumping robots for irregular terrains. As a primary contribution, and unlike previous studies that focus exclusively on the propulsion phase, this work addresses all stages, using direct servomotor actuation without mechanical energy storage. Biological joint kinematics were mathematically characterized using Cubic Smoothing Splines. By empirically tuning the smoothing parameter (p), the trajectories achieved the continuous differentiability required for electromechanical actuation. These curves were implemented into a 3D multibody simulation (Altair Inspire), where a PID-based tracking framework managed the mechanically nonlinear multibody dynamics governing the jump (arising from contact forces, impacts, and time-varying inertial effects) to ensure stabilization during the complex landing phase. Validating the model against previous studies, the simulation successfully achieved a maximum horizontal jump distance of 24.12 cm (4.02 body lengths) and a peak velocity of 1.45 m/s. The kinematic fidelity of the model was mathematically validated, yielding a maximum Normalized Root Mean Square Error (NRMSE) of 4.121% relative to biological reference trajectories. Furthermore, the robustness of the landing and re-stabilization phases was demonstrated through a continuous double jump covering a total distance of 45.83 cm. Finally, a dynamic scaling analysis was performed to evaluate the feasibility of implementing real motors. Ultimately, this study establishes a mathematically robust framework for replicating frog-inspired jumping dynamics, contributing a transferable methodology for the design and control of articulated bio-inspired robotic systems. Full article

This paper assesses the role of nature-based solutions as a way to scale sustainability goals, focusing on the use of carbon credits in voluntary corporate climate commitments. To accomplish this, we adapt the DICE23 model by incorporating a demand function for voluntary corporate carbon abatement and by including the costs of supplying nature-based and non-CO₂ credits to that market. Through scenario analysis, we examine how likely current and proposed new commitments are to meet 1.5 °C and 2 °C climate thresholds by 2030 and 2050 with and without the use of nature-based carbon credits. We find that the inclusion of nature-based credits would increase the probability of meeting a 2 °C threshold by 2030 by lowering costs and significantly increasing overall mitigation. A key result of this paper is that allowing companies to utilize nature-based credits to deliver on near-term mitigation targets can provide the same number of emission reductions as efforts to expand corporate commitments three-fold, but is limited to reductions in the energy sector alone. Overall, incorporating forests and other nature-based credits into corporate commitments could provide immediate and substantial climate benefits while also supporting people and nature impacts today, enabling companies to better achieve multiple social and sustainability goals simultaneously. Full article

Ultra-high-speed cutting (UHSC) has emerged as a transformative manufacturing technology aimed at overcoming the long-standing machining challenges associated with high-performance difficult-to-machine composites (HPDMCs). These materials—comprising silicon-based, metal matrix, and carbon fiber-reinforced polymers—are critical to strategic sectors such as aerospace and high-end equipment. This review adopts a distinctive “material-tool-process-equipment” synergistic innovation framework as its core analytical lens. Within this framework, it systematically outlines advances in UHSC, including the fundamental mechanisms of damage suppression and surface integrity enhancement under ultra-high strain rates. Innovative process methods such as laser-assisted and ultrasonic-assisted machining are examined in detail. This review also provides a mechanistic analysis of two key enabling technologies—tool micro-texturing and functional coatings—highlighting their roles in interfacial tribological regulation and physicochemical protection. Furthermore, dedicated equipment systems and stability optimization strategies essential for technological implementation are presented and evaluated. By synthesizing the current state of the field, this review identifies persistent bottlenecks and, guided by the proposed framework, suggests targeted future research directions: deep integration of smart manufacturing technologies, development of synergistic multi-energy-field processing, and enhanced adaptability to extreme service environments. This work not only consolidates the current knowledge in UHSC but also outlines a clear pathway for its evolution into a fully autonomous, efficient, and reliable manufacturing paradigm. Full article

Electric vehicles are becoming more common daily because countries are moving towards net-zero emissions. Different generations of NMC battery cells are used for EV applications. This work investigates the degradation behavior of high-energy 75 Ah prismatic NMC631 lithium-ion cells using a combined incremental capacity analysis (ICA) and electrochemical impedance spectroscopy (EIS) framework under different conditions. Cells are cycled at an identical C-rates and depths of discharge (DoD), and at different temperatures to systematically evaluate the impact of temperature on electrochemical aging. ICA results revealed that cells cycled at low temperatures maintain stable peaks and a high SoH (>90%) after completing 1600 full equivalent cycles (FECs). EIS analysis confirms the distinct impedance evolution patterns. Degradation mode analysis is performed using the ICA, and EIS highlights the combined evolution of conductivity loss, loss of lithium inventory, and loss of active material. It also highlights different degradation path trajectories under identical operating conditions stem from the progressive amplification of internal cell heterogeneities during aging. The results demonstrate that combining ICA and EIS provides complementary insights into degradation evolution and enables clear differentiation between gradual aging and sudden failure pathways in high-energy NMC cells. Full article

The power system is the backbone of the energy network, and overhead lines are its vital structures. Weather threats may jeopardise the reliability of lines and make them a weak link. In particular, heavy rainfall episodes can cause failures, especially in mountain areas. Current climate changes may exacerbate the effects on the ground, intensifying rainfall episodes and increasing the frequency of extreme events. In this context, debris flows triggered by rather intense precipitation and characterised by fast kinematics can destroy pylons and electric connections, affecting the infrastructures not only in the upper ridges but also downstream across the fan apex, where powerlines are much more distributed. This study presents an in-depth back-analysis of two debris flow events triggered in concomitance with a heavy cloudburst that occurred in Talamona (Sondrio Province, Italy) in July 2008 and in Campo Tartano (Sondrio Province, Italy) in April 2024. These events hit onsite powerlines, causing blackouts and showing the potential vulnerabilities of the local electricity system. An analysis of rainfall-induced landslide failure is carried out using the numerical model CRHyME (Climatic Rainfall Hydrogeological Modelling Experiment) and MIST-DF (Modelling Impulsive Sediment Transport—Debris Flow) with the aim of reconstructing the dynamics of the first (i.e., Talamona) geo-hydrological event. Powerline vulnerability is also investigated against debris flow dynamics, discussing possible strategies to reduce pylon exposure and to increase the resilience of the local electro-energetic network. Since, under climate change scenarios, heavy rainfall episodes are projected to intensify, an alternative approach based on rainfall-threshold curves is presented and applied to both cases of study. The latter, already implemented for civil protection purposes, could be useful in early-warning procedures against potential debris flow hazards. For both methodologies, the findings from the study confirm the strength of the approaches and foster their application in different situations (back-analysis and early warning) to reduce powerlines’ geo-hydrological risks. Full article

Background: Parents of children with attention-deficit/hyperactivity disorder (ADHD) and sleep problems can experience challenges and negative health effects. The aim of this study was to explore parents’ own health-related experiences as their child with ADHD and sleep problems underwent a sleep intervention with a weighted blanket. Methods: A convergent mixed methods design was undertaken. Sociodemographic and questionnaire data were collected from 68 parents at baseline and at the 16-week follow-up. Paired-samples t-tests were used to analyze the data. An inductive qualitative content analysis was used to analyze interviews with 21 parents after the follow-up. An integrative analysis was performed and assessed for confirmation, expansion, or disconfirmation. Results: At the follow-up, parents reported improvements in their own health status (EQ-5D-3L—index 0.83 ± 0.15 vs. 0.87 ± 0.13; p = 0.034), in well-being (Outcome Rating Scale—individual 7.08 ± 2.22 vs. 7.55 ± 1.82; p = 0.045), and in family life (the Brief Child and Family Phone Interview—family comfort score 5.62 ± 1.62 vs. 5.14 ± 1.66; p = 0.003). Parents’ health-related experiences were described as: (1) having a sense of well-being, including being well rested, sustaining energy, reaching a state of calm, and finding hope, (2) balancing family life, including reclaiming personal sphere and nurturing relationships, and (3) managing everyday life, including keeping to the daily schedule and dealing with household chores. The integrative analysis resulted in the overarching themes of health through: (1) inner strength (confirmed), (2) recovery (expanded), (3) close relationships (confirmed), and (4) social engagements (expanded). Conclusions: The findings suggest that sleep interventions for children with ADHD and sleep problems may also be associated with positive changes in aspects of parents’ health, well-being, and family life. Full article

In this paper, a hidden ring beam (HRB) joint suitable for steel-tube-reinforced concrete (ST-RC) composite columns is proposed. The seismic performance was evaluated experimentally by hysteresis loading tests on reinforcement anchorage construction and reinforced concrete (RC) slabs, which was evaluated by several indices to assess the strength, ductility, stiffness degradation and energy dissipation capacity. The results showed that the HRB joints have reliable seismic safety performance. The ultimate failure of all the specimens occurred in the plastic hinge regions of the RC beams. The specimens with different reinforcement anchorage construction methods exhibited excellent anchorage performance, maintaining effective anchorage between beam longitudinal bars and ring bars under cyclic loading. The RC slab increased the joint strength and the initial stiffness, with only a reduction in the ductility coefficient, and the average equivalent viscous damping coefficient reached 0.155. In addition, a joint numerical model was established, and the accuracy was validated against the test results, with the predicted strength differing from the test results by no more than 6%. A parametric analysis using numerical simulations revealed that the ring–longitudinal ratio, bearing stirrup diameter, RC slab constraints and axial load ratio were critical factors influencing the seismic performance of the joints. On the basis of the results of the parametric analysis, a moment capacity calculation method is proposed for HRB joints, providing a practical reference for seismic design in engineering applications. Full article

We develop a structural framework for the three-dimensional incompressible Navier–Stokes equations in which the nonlinear dynamics are reorganized in terms of triadic interactions, dyadic shells, and helical modes. Within this formulation, all interactions are classified into Low–Low, Low–High, and High–High channels, and it is shown that the Low–Low and Low–High contributions are perturbatively controlled through scale-localized estimates without introducing external assumptions. Consequently, potentially non-perturbative contributions are confined, within the present framework, to a class of same-scale High–High interactions. This class is further reduced, through geometric and dynamical constraints, to a coherent core characterized by amplitude activity and low phase drift. The resulting reduced dynamics is expressed in terms of family-level phase variables and associated curvature quantities. The main result establishes a quantitative residence-time compression principle for this coherent regime. Specifically, it is shown that intervals on which both amplitude activity and low phase drift persist must have small total measures, due to an absolute-value coercivity property of the curvature combined with bounded-variation control of the phase dynamics. This implies that coherent same-scale interactions cannot occupy a macroscopic portion of any bounded time interval, even though local re-entry into low-drift configurations is not excluded. Consequently, the nonlinear transfer associated with coherent triads becomes temporally localized and admits a shellwise compressed representation. These results provide a structurally reduced description of a candidate mechanism for cumulative same-scale amplification within the present dyadic–triadic framework. They do not claim a framework-level structural exclusion of the global regularity problem. Rather, they identify and analyze, within an explicit structural setting, a minimal mechanism for non-perturbative amplification, and establish a quantitative constraint on its temporal persistence. Full article

In the present paper, In₂O₃ NPs were synthesized by a wet-chemical method, in the absence and presence of the surfactant, and deposited as thin films on silicon substrates. After deposition, the films were subjected to rapid thermal annealing (RTA) at 550 °C, 750 °C, and 900 °C, for 300 s, under an inert atmosphere. The correlation between the morphological, structural, and optical characteristics, the wetting capacity of In₂O₃ films synthesized under different synthesis conditions, and the influence of the RTA treatment are presented. The vibrations of In-O bonds for In₂O₃ samples were confirmed using FTIR spectroscopy. Structural analysis shows that In₂O₃ NPs have a cubic crystalline structure, but with the increase in temperature at 900 °C, diffraction peaks characteristic of the tetragonal phase of indium appear, correlated with a decrease in lattice parameters, as a result of the crystallinity. The morphology of the In₂O₃ samples was studied by SEM, revealing predominantly spherical and uniformly distributed particles with nanometric sizes. The absorption spectra of the In₂O₃ NPs showed peaks in the ultraviolet region, and the high energy bandgap value of the In₂O₃ films varied between 3.28 and 4.33 eV, depending on the samples and RTA treatment. The contact angle measurements of In₂O₃ films determined the wetting capacity of the surface, reflecting changes in surface morphology and structure induced by the RTA process. The results suggest that In₂O₃ thin films with spherical nanoparticles, good wettability, and percolation can be used for the development of sensors with increased selectivity and sensitivity. Full article

High-temperature stress severely reduces the photosynthetic efficiency of radish (Raphanus sativus L.), a cool-season crop. This study evaluated five nitrogen (N) levels {0 N, 0.5 N, 1 N (234 kg urea ha⁻¹, based on RDA), 2 N, and 4 N} through an open-field experiment under high-temperature stress conditions. Analysis of OJIP transients revealed that high temperatures severely inhibited photosynthetic capacity in the 0 N, 0.5 N, and 4 N treatment groups. These groups exhibited a simultaneous increase in K and J-steps, signifying electron transport bottlenecks and structural damage to the oxygen-evolving complex (OEC). Consequently, energy absorption and trapping decreased, while heat dissipation increased. In contrast, the 2 N treatment maintained superior F_m(maximum fluorescence) and energy flux, demonstrating enhanced photosynthetic resilience. However, despite improved photosynthetic stability, the 2 N group did not show a significant increase in yield compared to the 0.5 N or 1 N treatment groups. These results suggest that photosynthetic protection under heat stress does not necessarily guarantee higher yields, highlighting the need to identify optimal fertilization points for sustainable production. Overall, the findings of this study provide fundamental data for strategic nitrogen management in open-field radish cultivation to mitigate the impacts of increasing climatic instability. Full article

Mandarin production has expanded rapidly in Türkiye in recent years, while climatic conditions in major citrus-growing regions have shifted. This study examines how climate variability relates to mandarin production using a provincial panel dataset covering the period 2004–2023. The analysis includes ten provinces that account for almost all national output. Mean annual temperature and total precipitation are used as climatic variables, alongside economic factors such as population, agricultural energy use, and lagged producer prices. Panel data models are employed to capture both temporal and regional variation, incorporating climatic and economic factors, including adaptation-related conditions such as agricultural energy use. The results show a consistent negative relationship between temperature and mandarin production, indicating that higher temperatures are associated with lower output levels. Precipitation does not exhibit a statistically significant effect, which likely reflects the widespread use of irrigation systems that reduce direct dependence on rainfall in citrus production. Economic variables are positively associated with production, suggesting that market conditions and production intensity also shape output dynamics. The findings point to temperature as the main climatic constraint in Mediterranean citrus systems and indicate that rising temperatures may increase production risks in coastal regions. These results contribute crop-specific evidence to the climate–agriculture literature and highlight the need to consider both climatic and economic factors when evaluating the sustainability of fruit production systems. Full article