Search Results (3,800)

Mountain ecosystems are susceptible to climate change, and alpine treeline ecotones (ATEs) represent one of the significant responsive indicators of climate-driven environmental change. This study examines long-term spatiotemporal dynamics of the ATE across the Eastern Slopes of the Canadian Rocky Mountains (ESCR) from 1984 to 2023, with the objective of assessing whether regional climate warming has influenced ATE extent and elevation across different aspects and watersheds. Multi-decadal Landsat imagery, ERA5-Land temperature data, and topographic variables were integrated within a Google Earth Engine (GEE) framework to map ATEs using the Alpine Treeline Ecotone Index (ATEI), a probabilistic approach designed to capture transitional vegetation zones. Temporal trends were evaluated using non-parametric statistics, correlation analyses, and watershed- and aspect-based comparisons. Results indicate that the total alpine treeline ecotone (ATE) area in the ESCR was approximately 13.3% larger in 2023 than in 1984. However, the temporal evolution of ATE extent and elevation was non-monotonic, and linear trend analyses did not detect statistically significant increasing or decreasing trends over the full study period. ATE elevation and expansion exhibited pronounced spatial heterogeneity, with greater changes occurring on north- and northwest-facing slopes and within selected watersheds. In contrast, summer (July–September) temperatures increased significantly (+2.84 °C), exceeding global land-only warming rates, and vegetation greenness (NDVI) showed a strong, statistically significant positive relationship with temperature. These findings show that while climate warming has clearly increased vegetation productivity, elevational ATE dynamics remain spatially heterogeneous and temporally non-synchronous with summer temperature trends. Full article

Polyelectrolyte microcapsules (PMCs) fabricated by layer-by-layer assembly require predictable shell stability for applications in drug delivery, biosensing, and environmental remediation. While core template type is known to influence stability, the role of polyelectrolyte layer number in governing poly(allylamine hydrochloride) (PAH) desorption remains poorly understood. This study quantitatively assessed PAH desorption from fluorescein isothiocyanate (FITC)-labeled shells of PMCs templated on CaCO₃ or MnCO₃ cores with 7, 9, or 13 layers under varying ionic conditions (distilled water, NaCl 0.2–3.0 M, Na₂SO₄ 0.005–1 M) over 168 h. Short-term incubations revealed no significant layer-dependent desorption differences for either core type. However, prolonged exposure uncovered a non-monotonic relationship for CaCO₃-templated PMCs: 7-layer capsules exhibited high initial but limited subsequent release (<50% increase), 9-layer capsules showed minimal initial dissociation followed by maximal kinetic amplification (up to 2000% increase), and 13-layer capsules displayed intermediate behavior. In contrast, MnCO₃-templated PMCs demonstrated uniformly low initial dissociation with gradual time- and concentration-dependent release irrespective of layer number. These findings establish core template nature as the dominant factor controlling dissociation kinetics, while layer number enables fine-tuning of release profiles—particularly for CaCO₃ systems—providing design principles for controlled-release applications requiring delayed or sustained payload delivery. Full article

Thermal excursions during post-weld heat treatment (PWHT) and on-site fabrication frequently compromise the integrity of Grade 92 steel. While hardness fluctuations are documented, the correlation between initial properties and long-term creep stability remains controversial. This study aims to evaluate the relationship between thermal history and subsequent creep performance. Heat treatments of T92 steel across a wide temperature range (760–1000 °C) were performed, followed by creep tests at 600 °C/130 MPa and microstructural characterization. Results reveal a non-monotonic evolution of hardness and strength, reaching a minimum at 850 °C due to martensitic lath recovery into ferrite, but nearly doubling the as-received (AR) values above 900 °C due to fresh martensite formation. Creep life drops to a minimum at 850 °C and recovers to the AR level at 950 °C. A significant “decoupling” occurs at 1000 °C, where the sample possesses the highest hardness but only exhibits one-fourth the life of the 950 °C sample. Superior performance stems from the retained M₂₃C₆ and its dynamic precipitation, which pins dislocations to form micro-lath structures. Conversely, 1000 °C facilitates full carbide dissolution, accelerating dislocation recovery. These findings emphasize precise PWHT control and demonstrate that a 950 °C rejuvenation treatment can restore over-tempered or damaged components. Full article

Here we perform a detailed information-theoretic (IT) analysis of atomic electron densities in the periodic table, from hydrogen (Z = 1) to lawrencium (Z = 103). By use of the Shannon entropy, the Fisher information and the disequilibrium functionals in both position and momentum spaces as fundamental descriptors of the atomic densities, the periodic table can be represented in a three-dimensional information space as a continuous, highly ordered manifold. The analysis shows that chemical periodicity naturally emerges as a helicoidal manifold (reminiscent of a helix) at the coordinates of a 3D theoretic-information space (Shannon, Fisher, Disequilibrium), with each period forming one segment within the continuous global trajectory. We find information-theoretic signatures of shell structure, sub-shell filling, and electron-configuration anomalies, such as the familiar irregularities seen in chromium and copper. Therefore, the helicoidal character emerges naturally and is not imposed a priori. Further, through the uncertainty principle of the complementary analysis in momentum space, more insights are gained by exposing maximal information-theoretic differentiation for lighter atoms and compression among heavy elements. Notably, momentum-space analysis reveals that hydrogen occupies a natural intermediate position between helium and lithium based on kinetic energy distribution—contrasting with IT position-space results that emphasize hydrogen’s unique delocalized electron density. Indeed, the 3D IT representation of the elements in position space aligns with the view that H does not belong to either the alkali metals or the halogens, but rather stands as a unique, standalone element. This complementary perspective provides new quantitative support for understanding hydrogen’s dual chemical nature, providing new quantitative insight into ongoing debates about hydrogen’s optimal periodic table position. Furthermore, by considering triadic relationships and complexity properties in relation to the López–Mancini–Ruiz (LMC) and Fisher–Shannon (FS) functionals, we show that atomic complexity increases monotonically along with nuclear charge, and we provide a quantitative measure of how organized atomic electron densities are distributed throughout the periodic system. Based on our IT analyses, the fundamental character of periodicity could be addressed by employing helicoidal representations that highlight the characteristics of hydrogen, while simultaneously preserving the autonomy of the blocks of elements. Full article

In this study, density functional theory (DFT) within the generalized gradient approximation (GGA) is employed to investigate the structural, electronic, mechanical, and thermoelectric properties of perovskite hydrides XZrH₃ (X = Mg, Ca, Sr, Ba). Mechanical stability and ductility are evaluated through the Cauchy pressure, Pugh’s ratio, and Poisson’s ratio, all of which point to ductile behavior with a dominant ionic-bonding character. Electronic structure calculations reveal metallic behavior arising from band overlap at the Fermi level. Equilibrium energy–volume data are fitted with the Murnaghan equation of state, and transport coefficients are extracted using the BoltzTraP package as implemented in WIEN2k. The absence of a band gap and the overlap between valence and conduction bands confirm conductor-like behavior. Lattice thermal conductivity for MgZrH₃, CaZrH₃, SrZrH₃, and BaZrH₃ increases monotonically with temperature. Overall, the results identify MgZrH₃ in particular as a promising candidate for thermoelectric devices and solid-state hydrogen storage, thereby supporting progress toward a sustainable hydrogen economy. Full article

Al₂O₃-Cu ceramic-metal composites containing 2.5 vol.% of a metallic phase were fabricated using the Pulse Plasma Sintering (PPS) method in order to evaluate the influence of sintering temperature on densification, microstructure, and mechanical performance. Consolidation was carried out at 1200 °C, 1250 °C, 1300 °C, and 1400 °C under uniaxial pressure with a short sintering time of 3 min. Regardless of the processing temperature, all composites exhibited very high relative densities exceeding 99% of the theoretical value, indicating the high efficiency of PPS in densifying Al₂O₃-Cu systems while suppressing copper leakage. X-ray diffraction confirmed the presence of only two phases, Al₂O₃ and Cu, with no secondary reaction products. Microstructural observations revealed irregular copper particles and areas of dispersed metallic phase, whose proportion decreased with increasing sintering temperature due to accelerated matrix densification and copper immobilization. Grain growth in the alumina matrix was strongly temperature-dependent, with the average equivalent grain diameter increasing from 0.49 µm at 1200 °C to 2.35 µm at 1400 °C. Hardness decreased from 19.5 ± 2.8 GPa to 12.2 ± 1.6 GPa with increasing temperature, whereas fracture toughness reached a maximum of 5.42 ± 0.65 MPa·m0.5 at 1400 °C. The highest strength under monotonic compression conditions was obtained for samples sintered at 1300 °C, indicating an optimal balance between densification and microstructural coarsening. These results demonstrate that PPS is an effective method for producing dense Al₂O₃-Cu composites with tailored microstructure and mechanical properties. Full article

Sliding Mode Control (SMC) is a widely used controlling method in the field of current attitude control of launch vehicles. The effectiveness of reaching the Sliding Surface could influence the effect of the attitude control. Aiming to derive better control quality of attitude angles to launch vehicles by investigating the correlation between rise time, maximum overshoot, settling time, respond speed, and motion smoothness, a novel Comprehensive Evaluation Index Function (CEIF) was designed for balancing response speed and motion smoothness. Further, based on this CEIF, both the control characters influenced by the Constant Reaching Law and those characters influenced by the Power Reaching Law were used to propose the Constant Power Reaching Law (CPRL). Then, a fast terminal sliding mode controller was developed. In the simulation, regardless of when the launch vehicle attitude faults occurred, the CEIF with Monotonic Increase in Each Independent Variable could clearly and accurately represent the control quality of launch vehicle attitude. The fast terminal sliding mode controller (FTSM controller) with CPRL could provide better quality of attitude fault-tolerant control compared with a series of FTSM controllers with different currently established reaching laws. Full article

3D electrodeposition printing is an emerging process for fabricating metallic parts with controllable geometry, yet the coupled influences of electrochemical kinetics, ion transport, and tool motion on layer height remain difficult to interpret. This work presents a physics-based process model that links key process inputs, current density, electrolyte concentration, the inter-electrode gap, and tool scanning speed, to the resulting layer height in 3D electrodeposition printing of nickel-based structures. The model combines species transport in the inter-electrode gap with Butler–Volmer kinetics, under carefully stated assumptions regarding current efficiency, overpotential, and lateral spreading. Model predictions are validated against experimentally reported layer heights over a range of process conditions, yielding average errors (9–15%) and root-mean-square errors (0.13–0.28 µm) that demonstrate good agreement and highlight the impact of simplifying assumptions. Systematic parametric studies reveal how each process input monotonically influences layer height in ways consistent with Faraday’s law and diffusion-controlled growth, while also quantifying the relative sensitivity to different parameters. Building on these results, we introduce a dimensionless 3D Electrodeposition Printing Index that consolidates the key process and material parameters into a single scalar describing the geometric growth regime. The index enables construction of process maps that capture how combinations of current density, scan speed, concentration, and gap affect achievable layer height within the validated operating window. The scope and limitations of the proposed modeling framework and the index, particularly regarding other materials, more complex geometries, and pulsed or strongly convective regimes, are explicitly discussed, providing a basis for future model extensions and experimental validation. Full article

Multi-modal sentiment analysis (MSA) aims to accurately identify users’ emotional states by integrating textual, acoustic, and visual modalities. However, existing methods often suffer from insufficient cross-modal interaction, rigid fusion strategies, and limited sensitivity to subtle sentiment-level differences, which severely restrict model generalization and robustness. To address these issues, this paper proposes CrossSent, a multi-modal sentiment analysis framework that combines cross-modal attention with pairwise ranking regularization. Specifically, a Gated Multi-modal Residual Adapter (GMRA) is introduced to dynamically integrate heterogeneous features through gated residual connections, effectively mitigating modality asynchrony and noise interference. Meanwhile, a Monotonic Pairwise Ranking (MPR) regularization enhances discrimination among fine-grained sentiment levels. Furthermore, an Error-Interval Ordinal Inconsistency (EIOI) loss is designed to tolerate small prediction deviations, improving both stability and robustness. Experimental results on CMU-MOSI, CMU-MOSEI, and CH-SIMS demonstrate that CrossSent consistently surpasses state-of-the-art baselines across key metrics. For instance, it achieves 89.78% binary accuracy and 52.1% seven-class accuracy on CMU-MOSI, 87.72% and 54.7% on CMU-MOSEI, and 80.41%, 62.36%, and 43.54% for three- and five-level CH-SIMS tasks, with reduced mean absolute errors of 0.563, 0.513, and 0.408, respectively. We further report ordinal-consistency measures (QWK and level-jump statistics) to complement conventional metrics and quantify level-wise agreement. These results validate the effectiveness and generalization capability of the proposed framework. Full article

Field-scale nitrogen migration mechanisms in small watersheds remain poorly quantified due to insufficient representation of microtopographic heterogeneity. This study investigates nitrogen transport dynamics in a 1.27 km² agricultural watershed in China’s Jianghuai region using unmanned aerial vehicle (UAV) -derived 0.1 m digital elevation models (DEMs) and coupled hydrological–erosion modeling. The Soil Conservation Service Curve Number (SCS-CN) and Modified Universal Soil Loss Equation (MUSLE) models quantified nitrogen output loads, while the multi-flow direction algorithm simulated migration trajectories for total nitrogen (TN), ammonium, and nitrate. Results revealed strong spatial heterogeneity in nitrogen exports (watershed mean: 29.66 kg TN/km²·a), with bare land and greenhouses exhibiting the highest outputs (448.54 and 363.41 kg/km²·a) and forested areas showing minimal export (<6.1 kg/km²·a). Nitrogen migration was predominantly controlled by topographic gradients, with microtopographic features—field ridges, ditches, and buildings—physically redirecting flows and creating critical export nodes at field boundaries. DEM resolution critically affected simulation accuracy: erosion intensity displayed a non-monotonic response with an inflection point near 1 m resolution, corresponding to the median elevation difference (1.2 m) of field ridges. Structural equation modeling confirmed that high-resolution DEMs (0.1–2 m) maintained topographic control over nitrogen migration (~80% contribution), whereas 30 m DEMs reduced this influence to 30%, inducing spurious meteorological dominance. This study demonstrates that decimeter-scale DEMs are essential for accurately capturing microtopographic regulation of nitrogen transport, providing a methodological basis for precision management of agricultural non-point source pollution. Full article

This study investigates how outlet pressure influences the fire suppression performance of a compressed air foam system (CAFS), with the aim of supporting system optimization and engineering applications. An experimental apparatus for foam performance testing is used to measure changes in foam flow rate, expansion, initial velocity, initial momentum, and drainage time at different outlet pressures. On the basis of relevant theoretical models, the factors causing discrepancies between model predictions and experimental results are examined, and the models are then refined. How the outlet pressure of CAFS affects foam performance is thereby clarified. The results show that foam flow rate increases as outlet pressure increases. At higher pressures, shear-thinning and intensified gas–liquid mixing affect the foam. As a result, the growth of flow rate in the range of 0.01–0.03 MPa is significantly higher than that in the range of 0.06–0.10 MPa. Both initial velocity and initial momentum increase significantly with increasing pressure, whereas the expansion decreases. Within the outlet pressure range of 0.01–0.10 MPa, the initial velocity increases from 1.23 m/s to 6.65 m/s, the initial momentum rises from 4.6 kg·m/s to 34.1 kg·m/s, and the expansion decreases from 9.2 to 5.4, indicating reduced foam stability. Drainage time and drained mass vary non-monotonically with outlet pressure. The longest drainage time and the smallest drained mass occur at 0.06 MPa. Fire suppression performance improves as outlet pressure increases. A higher outlet pressure enables the foam solution to penetrate the flame zone more effectively and to cover the surface of the burning material. In addition, changes in foam properties enhance the thermal insulation and smothering effects of the foam layer, as well as its heat absorption and cooling capacity. These effects together improve the efficiency of fire source cooling. Full article

Sliding contact wear at the pantograph–catenary interface directly impacts the current collection performance and power supply reliability of electrified railways. Addressing the challenges in multi-environmental wear studies—namely, fragmented modeling chains, inconsistent parameter calibrations, and prohibitive computational costs that hinder horizontal comparisons—this study develops an equivalent parameterized modeling framework tailored for engineering assessment. The framework encapsulates environmental effects as equivalent load increments and interface coefficient corrections, facilitating efficient multi-scenario parameter scanning within a 3D contact model. Findings reveal that environmental factors drive wear through a distinct “pressure-wear” nonlinear decoupling mechanism. In sandy environments, abrasive-mediated micro-cutting dominates, leading to a monotonic surge in wear depth as sand concentration increases, despite a buffered contact pressure response. In icing conditions, the synergy of low-temperature brittleness and geometric impact renders hotspot wear highly sensitive to temperature fluctuations. For salt spray conditions, the environmental impact is represented via equivalent corrections to the interfacial parameters; within this equivalent framework, the results suggest that salt spray intensity has a more pronounced effect on wear accumulation than humidity alone. This work reveals the divergence of dominant damage pathways across environments, offering a quantitative basis for the differentiated maintenance and remaining life estimation of pantograph–catenary systems in extreme climates. Full article

The corrosion behavior of pipeline steels in marine environments is strongly affected by hydrodynamic conditions and microbial activity, yet their coupled influence remains insufficiently understood. In this study, the corrosion behavior of X70 pipeline steel was systematically investigated in flowing artificial seawater over a velocity range of 0–1.5 m/s, under both sterile conditions and in the presence of Pseudomonas aeruginosa. Corrosion weight loss measurements, electrochemical techniques, and surface characterization were employed to evaluate flow-dependent corrosion evolution. The results show that flow velocity plays a dominant role in regulating corrosion behavior. Under sterile conditions, increasing flow velocity enhances mass transfer and surface renewal, leading to progressively increased corrosion severity. In the presence of P. aeruginosa, corrosion behavior exhibits a non-monotonic dependence on flow velocity. Lower flow velocities are associated with reduced corrosion rates and relatively uniform surface degradation, whereas moderate flow velocities promote localized corrosion and increased pitting severity. At higher flow velocities, strong hydrodynamic effects suppress the retention of corrosion products and microbe-associated surface layers, resulting in corrosion behavior primarily controlled by fluid flow. Overall, the results indicate that microbial presence modifies the flow–corrosion relationship of X70 steel by altering interfacial conditions under low-to-moderate flow regimes. Full article

Global, industrialization-driven environmental bottlenecks push manufacturing enterprises toward green transitions; yet, the information asymmetry between central and local governments, and between enterprises and banks, hinders this process. Adopting a systemic–synergistic perspective integrating decentralized governance and green credit, in this study, we investigate the green transition decisions of manufacturing enterprises. We construct a quadrilateral evolutionary game model involving the central government, local governments, enterprises, and banks, employing MATLAB R2022b to simulate the effects of the key parameters. Subject to the model’s structural assumptions and parameter boundaries, three core findings emerge: first, we find that punitive environmental policies outperform incentive-based instruments in driving enterprise emission reduction; second, we find that the adaptive adjustments made by decentralized governance can effectively facilitate green practices among enterprises; third, within this framework, we find that green credit exerts a non-monotonic impact on enterprises’ green transition behaviors; meanwhile banks’ assessments of enterprises’ environmental risks can indirectly promote enterprise abatement by motivating local governments through signal transmission. This study underscores the systemic synergy of decentralized governance and green credit, offering insights for multistakeholder coordination and policy optimization to advance organizational sustainability transitions for the green economy. Full article

Underwater wireless power transfer (UWPT) operates under special conditions, where the conductivity of seawater introduces eddy current losses, thereby reducing system efficiency. Meanwhile, the design parameters of magnetic couplers significantly influence their transmission characteristics. This paper proposes a fast and accurate neural network prediction model for mutual inductance and losses of magnetic couplers based on mirror-method prior knowledge within a prior knowledge input (PKI) framework. The proposed model integrates a low-fidelity analytical model with data-driven learning to achieve high prediction accuracy while maintaining computational efficiency. Based on the developed model, the transmission characteristics of unipolar rectangular and bipolar DD magnetic couplers are systematically investigated. The results indicate that the rectangular couplers exhibit higher overall efficiency than the DD couplers, with a more monotonic variation in efficiency under design constraints. Owing to its structural characteristics, the DD couplers present an optimal current-carrying area ratio, which is approximately 0.85 within the parameter range. Experimental validation is conducted at a 1 kW power with outer dimensions of 200 mm × 250 mm. The optimal transfer efficiencies of the rectangular and DD couplers reach 97.33% and 96.19%, respectively. The experimental results show good agreement with both simulations and model predictions, demonstrating the reliability of the proposed method for UWPT magnetic coupler analysis. Full article