Search Results (20,056)

This study applies reinforcement learning to search parameter regimes that yield chaotic dynamics across six systems: the Logistic map, the Hénon map, the Lorenz system, Chua’s circuit, the Lorenz–Haken model, and a custom 5D hyperchaotic design. The largest Lyapunov exponent (LLE) is used as a scalar reward to guide exploration toward regions with high sensitivity to initial conditions. Under matched evaluation budgets, the approach reduces redundant simulations relative to grid scans and accelerates discovery of parameter sets with large positive LLE. Experiments report learning curves, parameter heatmaps, and representative phase portraits that are consistent with Lyapunov-based assessments. Q-learning typically reaches high-reward regions earlier, whereas SARSA shows smoother improvements over iterations. Several evaluated systems possess equation-level symmetry—most notably sign-reversal invariance in the Lorenz system and Chua’s circuit models and a coordinate-wise sign pattern in the Lorenz–Haken equations—which manifests as mirror attractors and paired high-reward regions; one representative is reported for each symmetric pair. Overall, Lyapunov-guided reinforcement learning serves as a practical complement to grid and random search for chaos identification in both discrete maps and continuous flows, and transfers with minimal changes to higher-dimensional settings. The framework provides an efficient method for identifying high-complexity parameters for applications in chaos-based cryptography and for assessing stability boundaries in engineering design. Full article

In coal mine non-solidly grounded systems, high-impedance faults generate minimal zero-sequence currents with obscured characteristics and strong interference, complicating faulted line identification. Existing methods rarely address three-phase imbalance and variable cable parameters, causing selection errors. To this end, a method for identifying the non-effective ground fault routing of mining cables based on Steady-State Impedance Analysis (SSIA) and Holmes–Duffing oscillator small-signal detection is proposed. Firstly, based on SSIA, the mapping relationship that the phase of the zero-sequence current variation in the faulted line is the same as the phase of its voltage relative to the faulted ground is derived before and after the occurrence of the fault. Meanwhile, identifiable differences exist in both phase and amplitude of the zero-sequence current change in faulty lines compared to non-faulty lines before and after fault occurrence. This is used as the criterion for high-impedance ground fault line selection. In the mining environment, zero-sequence current variations are characterized as weak signals, which poses significant challenges for detection. Thus, a Holmes–Duffing oscillator weak signal detection method is proposed. Based on chaotic principles, accurate line selection is achieved by diagnosing chaotic states in oscillator-generated phase trajectories. A specific mine grid simulation via MATLAB/Simulink 2023b validates the method’s efficacy and applicability. Full article

Nickel–tungsten carbide (Ni/WC) multi-pass fused cladding layers with different cerium (IV) oxide (CeO₂) contents were applied to Cr12MoV cold work tool steel surfaces using the coaxial powder feeding method for laser cladding. Scanning electron microscopy, energy spectrum analysis, X-ray diffraction, and wear experiments were conducted to study how adding CeO₂ to change the properties of WC-reinforced Ni-base composite coatings in turn alters the microstructure and properties of Cr12MoV cold work tool steel. The results show that laser cladding is effective when the process parameters are as follows: a power of 1500 W, a 24 mm defocusing distance, a 6 mm/s scanning speed, a 5 mm spot diameter, and a powder delivery of 0.1 g/s. Laser-fused cladding coatings are mainly composed of dendrites, crystalline cells, strips, and bulk microstructures. The addition of CeO₂ is effective at improving the microstructure and morphology of the coating—the size and distribution of the reinforcing phase change very significantly, and the shape changes from irregular and lumpy to spherical. With a 2% CeO₂ content, the enhanced phase, now spherical and white, is more diffusely distributed in the tissue. The maximum microhardness of the composite-coated specimen after the addition of CeO₂ is about 986 HV, which is approximately 20% higher than the hardness of the composite coating with no CeO₂ added. Full article

Background: Amyloid positron emission tomography (PET) has been proposed as a tool to monitor myelination in multiple sclerosis (MS). We present baseline results from an ongoing prospective study, which is the first to include both early and standard phases of amyloid PET in patients with newly diagnosed MS. Methods: The prospective study includes patients with newly diagnosed MS (January 2023–February 2024). Clinical evaluation includes neurological disability (EDSS) and neuropsychological assessment. Brain MRI, early [¹⁸F]florbetaben (FBB) PET (eFBB; 0–5, 0–10 min post-injection), and standard FBB PET (sFBB; 90 min post-injection) were acquired. Normal-appearing white matter (NAWM) and damaged white matter (DWM) in MRI were segmented and co-registered with PET images. Results are presented as standardized uptake values (SUV), with the ratio using cerebellum as the reference region (SUVR) and the percentage of change between the DWM and NAWM. Results: Twenty patients were included (35.05 ± 10.72 years; 75% women). Both eFBB and sFBB acquisitions showed significantly lower SUVRmax and SUVRmean, and higher SUVRmin in the DWM compared to NAWM (p < 0.001) in all patients. SUV parameters in both DWM and NAWM from eFBB and sFBB PET correlated with the number of relapses and EDSS (r = −0.454 and r = −0.446, respectively; p < 0.05). Additionally, SUVR values in the DWM during eFBB correlated with cognitive impairment (SDMT; r = −0.516, p < 0.01), fatigue (MFIS-5; r = −0.450, p < 0.05), and quality of life (EQ-5D; r = −0.490, p < 0.05). Conclusions: Quantitative analysis of dual-phase FBB PET demonstrates differential uptake between DWM and NAWM, which is probably associated with demyelination and neurodegeneration. These preliminary findings suggest that amyloid PET may have predictive value for disease activity and progression, supporting its potential as a biomarker in MS. Follow-up data from this study are needed to support the baseline results. Full article

The present work investigated the effect of different storage temperatures (10 °C, 30 °C, and 50 °C) on the mechanical, structural, chemical, and microstructural properties of a set of sustainable mortars with gray waste. Three types of mortar were investigated: (1) Type A, prepared from a proportion of 1 part cement: 1 part hydrated lime: 6 parts sand; (2) Type B, prepared from a proportion of 1 part cement: 1 part hydrated lime: 6 parts sand: 0.1 part waste; and (3) Type C, prepared from a proportion of 0.9 part cement: 1 part hydrated lime: 6 parts sand: 0.1 part waste. The waste incorporation reduced compressive strength by 8%, while partial cement replacement reduced by 33%. The cement storage at 10 °C preserved the compressive strength, whereas storage at 50 °C increased it by 8.8%. In type B mortar, the waste incorporation improved compressive strength by 19% at 50 °C. The most substantial enhancement occurred in type C mortar, where cement replacement with residue and storage at 50 °C led to a 27% increase. These results highlight the potential of higher storage temperatures to mitigate cement degradation in humid environments. Furthermore, XRD analysis revealed that cement storage temperature did not affect the formation of primary cement phases, as degradation products were chemically similar to hydration products. However, sustainable mortars exhibited changes in the C-S-H phase signal when the cement is stored for 90 days at 30 °C. Finally, SEM and EDS analyses identified variations in Ca, Si, and O proportions depending on storage conditions. Full article

The local energy balance at the liquid-solid front has been widely used in the literature. However, depending on the initial state of the system, the boundary conditions, and the thermodynamic properties of the phase change material, the local energy balance can lead to inaccuracies. The total energy balance has been applied to phase change processes; however, discrepancies have been reported regarding the dynamics of the melting front obtained through this approach. In this work, the concept of thermodynamic equilibrium is used to determine the exact liquid-solid coexistence state in adiabatic systems. Thermodynamic equilibrium of saturated mixtures is used to validate the proposed energy balance. We found that the melting front position obtained from a local energy balance can be underestimated by as much as $37.4\%$ when compared with the equilibrium value. In contrast, the interface position estimated by the total energy balance was in good agreement with equilibrium, with relative differences between $0.082\%$ and $0.11\%$. Finally, a melting experiment using paraffin RT50 was conducted in a thermally insulated cylindrical unit. The experimental front position was underestimated by the local energy balance, with differences between $2.4\%$ and $6.9\%$, while the total energy balance showed smaller discrepancies between $0.28\%$ and $5.71\%$. Full article

Drought stress during the reproductive phase substantially reduces seed yield and quality, posing a major challenge to sustainable crop production under climate change. This study investigated the effects of drought stress at the flowering stage on selected biochemical and physiological parameters in 18 carrot accessions. To describe the long-term consequences of drought comprehensively, we examined seed quality parameters. Our analyses revealed that stress responses are highly dependent on the genotype and the parameter examined. Regarding antioxidant responses and potential tissue damage caused by drought, ‘Dolanka’, DC97, DC265, DC359, DC522, DC701, DC704, and DC720 exhibited the highest tolerance. The photosynthetic apparatus and pigments were maintained under stress in DC233, DC522, DC717, and DC728. Germination parameters served as reliable indicators of stress tolerance in DC97, DC359, DC432, DC522, DC701, and DC722 accessions. Based on these findings and detailed discussion of the results, we conclude that tolerance/sensitivity assessment of carrot genotypes should consider the holistic response of the plant rather than individual parameters. Through overall assessment, we recommended DC522 accession as the most drought-tolerant, given its enhanced ROS (Reactive Oxygen Species) scavenging mechanisms, increased chloroplast pigments accumulation, and superior germination parameters under drought conditions. Conversely, DC295 should not be cultivated under water-deficient conditions due to its impaired ability to detoxify ROS, altered photosynthetic activity, and disrupted seed germination under such conditions. These results collectively highlight the potential for selecting drought-tolerant carrot genotypes in breeding programs targeting improved seed performance under water-limited conditions, thereby supporting the development of resilient cultivars adapted to future climate challenges. Full article

Materials that allow the storage of a significant amount of heat in a narrow temperature range by a solid–liquid or a solid–solid phase change are called Phase Change Materials (PCMs). Understanding the thermodynamics of PCMs is crucial in PCM R&D for identifying candidate materials, developing new PCMs, and optimizing known PCMs. In this work, a review of the use of entropy to understand the thermodynamics of pure substances as PCMs is performed. Among pure substances, water, alkanes, alkanols, and fatty acids are well-known. Because they give valuable information, elements are also included. While phase change enthalpy and temperature are easy to comprehend and are directly used for application, the opposite holds for entropy. Thus, entropy usually receives little attention. However, as this review shows, entropy is of central importance, and even if it is not analyzed explicitly, then it is implicitly included in the data. If explicitly used, it can reveal crucial information. This is shown by a review of analysis tools and their results from analyzing typical PCMs. The review shows that if entropy is used systematically, a significant improvement in the understanding of the thermodynamics of PCMs is possible. Full article

Passive design strategies incorporating phase change materials (PCM) provide effective thermal energy storage, improve indoor comfort, and reduce building energy demand. This study aimed to evaluate the effectiveness of partially filled PCM glazing systems in stabilizing indoor thermal comfort under Korean climate conditions, testing the hypothesis that partial integration can provide meaningful diurnal temperature regulation without compromising daylight access. Indoor air, interior and exterior glazing surfaces, and the PCM layer were monitored to evaluate heat transfer, while EnergyPlus simulations extended the analysis to seasonal conditions. The PCM model was developed using the Conduction Finite Difference (CondFD) algorithm and validated against experimental data, reliably reproducing dynamic phase change behavior. Field tests with a 28 °C PCM showed reductions in indoor peak temperatures of about 2.0 °C during daytime and increases of 1.5 °C at night. Under broader climatic simulations, the same PCM achieved up to 3.7 °C daytime reductions and 2.0 °C nighttime increases, depending on outdoor conditions. These findings highlight the potential of PCM-integrated glazing systems for adaptive thermal regulation in Korean climates and suggest broader applicability for passive cooling and heating strategies in buildings facing increasingly variable weather conditions. Full article

The aim of this work was to investigate the evolution of the mechanical integrity of the selected offshore oil reservoir during its life cycle. The geomechanical stability of the reservoir formation, including the caprock and base rock, was investigated from the exploitation phase through waterflooding production to the final phase of enhanced oil recovery (EOR) with CO₂ injection. In this study, non-isothermal flow simulations were performed during the process of cold water and CO₂ injection into the oil reservoir as part of the secondary EOR method. The analysis of in situ stress was performed to improve quality of the geomechanical model. The continuous changes in elastic and thermal properties were taken into account. The stress–strain tensor was calculated to efficiently describe and analyze the geomechanical phenomena occurring in the reservoir as well as in the caprock and base rock. The integrity of the reservoir formation was then analyzed in detail with regard to potential reactivation or failure associated with plastic deformation. The consideration of poroelastic and thermoelastic effects made it possible to verify the development method of the selected oil reservoir with regard to water and CO₂ injection. The numerical method that was applied to describe the evolution of an offshore oil reservoir in the context of evaluating the geomechanical state has demonstrated its usefulness and effectiveness. Thermally induced stresses have been found to play a dominant role over poroelastic stresses in securing the geomechanical stability of the reservoir and the caprock during oil recovery enhanced by water and CO₂ injection. It was found that the injection of cold water or CO₂ in a supercritical state mostly affected horizontal stress components, and the change in vertical stress was negligible. The transition from the initial strike-slip regime to the normal faulting due to formation cooling was closely related to the observed failure zones in hybrid and tensile modes. It has been estimated that changes in the geomechanical state of the oil reservoir can increase the formation permeability by sixteen times (fracture reactivation) to as much as thirty-five times (tensile failure). Despite these events, the integrity of the overburden was maintained in the simulations, demonstrating the safety of enhanced oil recovery with CO₂ injection (EOR-CO₂) in the selected offshore oil reservoir. Full article

Marine diatoms are an important group of phytoplankton that can shape marine ecosystems and global carbon cycling. When stressed, either physiologically or by grazing, diatoms release oxidized, lipid-derived signals known as oxylipins. Diatom-derived oxylipins are proposed to serve as defense and signaling chemicals that affect multiple components of marine ecosystems. Therefore, to elucidate the diversity of diatom-derived oxylipins produced during stress, we profiled the spectrum of dissolved lipids of five diatom species in culture under silicon limitation and across growth phases using ultra-high performance liquid chromatography coupled with high-resolution accurate mass spectrometry. In this study, we present evidence that physiological changes associated with Si-limitation elicit the extracellular release of linear oxygenated fatty acids (LOFAs) across five diatom species. For diatoms like Skeletonema japonicum and Pseudo-nitzschia multiseries, silicon limitation induced a distinct lipidomic signature driven by oxylipins known to be allelopathic. While their lipoxygenases were found to be different, S. japonicum and P. multiseries had the most similar dissolved lipidomes, suggesting alternative controls on oxylipin biosynthesis. Consequently, elevated oxylipin concentrations with silicon stress, estimated up to 5.91 µM, pose implications for diatoms at sea, potentially affecting ecosystems and biogeochemistry. Full article

Hispanic, Asian, and African Americans are disproportionately affected by liver cancer, viral hepatitis B (HBV), and viral hepatitis C (HCV), in part because of barriers to liver cancer awareness and prevention. We implemented a community-based, culturally tailored initiative to raise awareness and promote uptake of behaviors for liver cancer prevention, early diagnosis, monitoring, and treatment. Guided by community-based participatory research (CBPR) principles and built on well-established collaboration with community-based organizations, we actively engaged the community advisory board (CAB), community health workers, and community members in multiple phases of (1) a community-based educational initiative, (2) a city-wide bus campaign, and (3) community health fairs. This multilevel initiative saw notable changes in community members’ knowledge of liver cancer, viral hepatitis, lifestyle behaviors like dietary patterns, and uptake of screening tests for HBV/HCV. Additionally, the comprehensive engagement of CAB, healthcare workers, and community members significantly benefited community capacity building on cancer research and health promotion. These CBPR-guided community initiatives had remarkable positive impacts on promoting liver cancer awareness and prevention among underserved racial/ethnic minorities. The academic–community relationships built on and strengthened through shared power, mutual respect, and trust serve as the foundation for sustainable community growth and empowerment. Full article

Coalbed methane (CBM) development involves multiple interacting physical fields, and different coupling schemes can lead to distinctly different production behaviors. A thermo-hydro-mechanical model accounting for gas–water two-phase flow and matrix dynamic diffusion (TP-D-THM) is developed and validated, achieving an error rate below 10%. By embedding the numerically estimated reservoir physical parameters of the Qinshui Basin into the numerical model, multi-field couplings during CBM production, the evolution of physical parameters, and the depth-dependent effects on production characteristics were revealed. The main findings are as follows: The inhibitory effect of water on CBM recovery consistently exceeds the promoting effect of temperature. As burial depth expands, the inhibitory effect first diminishes, then intensifies, ranging from 19.73% to 28.41%, while the thermal promotion effect exhibits a monotonically increasing trend, fluctuating between 8.55% and 16.33% and stabilizing below 1000 m. Temperature and burial depth do not alter the trend in gas production rate. For equilibrium permeability, reproducing a decrease–increase–decrease rate pattern requires explicit inclusion of water and matrix-fracture mass exchange terms, which can explain why different scholars obtained varying gas production rate trends using the THM model. Matrix adsorption-induced strain is the primary control on permeability evolution, and temperature amplifies the magnitude of permeability change. The critical depth essentially reflects the statistical characteristics of reservoir petrophysical properties. A dimensionless critical depth criterion has been proposed, which comprehensively considers reservoir pressure, permeability, and a fractional coverage index. For burial depths ranging from 650 to 1350 m, the TP-D-THM model can be simplified to the gas-mechanical model accounts for matrix dynamic diffusion (D-HM) with an error below 5%, indicating that thermal and water effects nearly cancel each other. Full article

Thermal energy storage (TES) plays a vital role in advancing energy efficiency and sustainability, with phase change materials (PCMs) receiving significant attention due to their high latent heat storage capacity. Nevertheless, conventional PCMs face critical challenges such as leakage, phase separation, and low thermal conductivity, which hinder large-scale applications. Encapsulation strategies have been developed to address these issues, and bio-based composite materials are increasingly recognised as sustainable alternatives. Materials such as lignin, nanocellulose, and biochar, as well as hybrid formulations with graphene and aerogels, show promise in improving thermal conductivity, mechanical integrity, and environmental performance. This review evaluates bio-based encapsulation approaches for PCMs, examining their effectiveness in enhancing heat transfer, durability under thermal cycling, and scalability. Applications in solar energy systems, building insulation, and electronic thermal regulation are highlighted, as are emerging AI-driven modelling tools for optimising encapsulation performance. Although bio-based PCM composites outperform conventional systems in terms of thermal stability and multifunctionality, they still face persistent challenges in terms of cost-effectiveness, scalability, and long-term reliability. Future research on smart, multifunctional PCMs and advanced bio-nanocomposites is essential for realising next-generation TES solutions that combine sustainability, efficiency, and durability. Full article

Background/Objectives: The cerebellum is essential for motor coordination and has recently been implicated in sleep-related disorders. However, the neural mechanisms linking sleep disruption to motor dysfunction remain poorly understood. This study aimed to elucidate the roles of the deep cerebellar nuclei (DCN), particularly the lateral nucleus, in motor dysfunction induced by chronic sleep disruption (CSD). Methods: Using a validated mouse model of CSD with periodic sleep fragmentation induced by an orbital shaker during the light phase, we assessed neuronal activation via c-Fos immunostaining and performed chemogenetic manipulation of glutamatergic neurons within the lateral nucleus. Behavioral performance was evaluated using open-field and rotarod tests. Results: CSD selectively increased c-Fos expression in the lateral nucleus, with no significant changes observed in other DCN subregions. Chemogenetic activation or ablation of glutamatergic neurons in the lateral nucleus decreased locomotor activity in the open-field test and shortened latency to fall in the rotarod task. Conversely, chemogenetic inhibition of these neurons attenuated CSD-induced impairments, restoring locomotor performance toward control levels. Conclusions: Our findings provide direct experimental evidence that glutamatergic neurons in the lateral nucleus play a crucial role in mediating CSD-induced motor dysfunction. These results highlight the cerebellar contribution to the interplay between sleep and motor control and identify a potential target for therapeutic intervention in sleep-related motor disorders. Full article