Search Results (256)

This study presents a feature-scale cross-validation of the Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) cloud–aerosol discrimination (CAD) products using 9289 globally collocated Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations acquired between October 2018 and June 2023. The operational ATL09 and a U-Net convolutional neural network (CNN) products are evaluated against CALIPSO on a pixel-by-pixel basis using class-specific metrics. Agreement improves with decreasing along-track comparison-window width, which limits spatial divergence from the ground-track crossing, whereas agreement varies weakly and non-monotonically across the actual 0–10 min inter-satellite time separation. Agreement also depends strongly on the CALIPSO integration size used for layer detection, which affects both feature detectability and effective spatial resolution. Restricting the analysis to ±60° latitude markedly increases aerosol agreement, consistent with reduced influence from high-latitude ambiguities associated with blowing snow, diamond dust, and larger crossing angles, while cloud metrics change more modestly. At a 1-s comparison width and 5-km maximum CALIPSO integration scale, CNN–CALIPSO F1 exceeds ATL09–CALIPSO F1 by 0.027–0.045 globally, with all paired 95% confidence intervals above zero across cloud and aerosol classes under daytime and nighttime conditions; however, some differences within ±60° are not distinguishable from zero. These results show that agreement is governed not only by retrieval algorithms but also by differences in instrument characteristics, effective spatial resolution, and sampling strategy. The proposed collocation framework provides a basis for evaluating current and future machine-learning approaches for spaceborne lidar CAD. Full article

On 23 January 2024, the Mw 7.0 Wushi earthquake occurred along the Maidan Fault at the boundary between the southwestern Tianshan Mountains and the Tarim Basin. This event, together with its subsequent aftershocks, provides a valuable opportunity to investigate fault rupture, stress perturbation, and aftershock triggering within a continental fold-and-thrust belt. In this study, we inverted the coseismic slip distribution by jointly integrating Interferometric Synthetic Aperture Radar and Pixel Offset Tracking observations. The preferred fault geometry indicates a northwest-dipping fault with a dip of approximately 60°. The mean rake angle is about 46°, suggesting an oblique slip with both thrust and left-lateral components. The 2024 Wushi event, together with the 1902 Atushi M 8.2 earthquake, produced pronounced Coulomb stress changes on the surrounding faults, with positive stress increases exceeding 10 kPa. Combined with the GNSS-derived regional strain-rate field and the interseismic fault-locking model, these results indicate elevated seismic potential on several surrounding fault segments, including portions of the Maidan Fault, Nalati Fault, North Wensu Fault, and Kalpintag Fault. We further examine the 2024 shallow Mw 5.7 aftershock, whose southeast-dipping surface rupture, together with the northwest-dipping mainshock fault, defines a typical pop-up structure. We also discuss the possible triggering of the 2025 Mw 5.8 Aheqi event by the stress perturbation associated with the Wushi mainshock. Our results highlight that the 2024 Wushi event substantially modified the regional stress field and influenced subsequent seismic activity, providing new insights into rupture segmentation, fault interaction, and seismic hazard in southwestern Tianshan. Full article

This paper presents a combined CFD and experimental investigation of water flow through a Shootfire-1000 water-foam fire monitor. The study aimed to assess pressure losses, flow characteristics, hydraulic stability, and cavitation risk, and to evaluate the influence of selected geometric and operating parameters on hydraulic performance. A numerical model based on the actual geometry of the device was developed and experimentally validated using pressure loss measurements obtained under representative operating conditions. The influence of flow rate, monitor elevation angle, water temperature, nozzle cone position, and cone plate fillet radius was analyzed. The results showed that the dominant pressure losses occur within the monitor head, particularly in the annular constriction formed by the nozzle cone and the housing. Water temperature and monitor elevation angle had only a minor effect on the overall hydraulic performance, whereas relatively small modifications of the nozzle cone geometry significantly affected pressure losses. The analyses further demonstrated that local geometric features play a key role in determining velocity distribution and hydraulic stability. No pressure values below the water vapour pressure were observed within the investigated operating range, indicating a negligible risk of cavitation. The results confirm that optimization of the monitor head geometry can effectively reduce hydraulic losses and improve the hydraulic performance of water-foam fire monitors. Full article

Low-elevation Doppler wind lidar scans, known as arc scans, extend traditional vertical-profile measurements to horizontal, off-site locations. This technique is designed to enable measurements at multiple distant locations relative to the instrument. Arc-scan methods have been widely utilized in wind energy applications and are also a promising tool for environmental monitoring for hazard assessment. This method introduces specific challenges absent in traditional vertical profile scans. The limited scan angle restricts the number of wind orientations available for reliable vector extraction. A reliable method of estimating the uncertainty intervals for retrieved wind speed and direction in operational configurations is thus of interest. Here, we developed a closed-form statistical expression for evaluating wind speed and direction prediction intervals. Because rapid-update operational scenarios (such as real-time dispersion modeling) yield a limited number of scans, the framework is specifically designed to remain mathematically robust and computable using only diagonal variance terms, bypassing the need for numerically unstable cross-covariance matrices. The expression was tested against a lidar and sonic anemometry measurement campaign. The wind-arc alignment emerges as a major influencing parameter impacting uncertainty of both direction and speed retrievals. Conclusions regarding scan parameters and siting considerations are drawn. Full article

Clay slopes are particularly sensitive to variations in soil strength, groundwater conditions, and slope geometry, making their rapid and reliable assessment essential for geotechnical design, landslide prevention, and infrastructure risk management. This study develops and evaluates an empirical express method for estimating the stability of clay slopes based on the relationship between soil mechanical parameters, slip surface geometry, and the factor of safety. The proposed approach derives empirical dependencies for the radius of the potential circular slip surface and the coordinates of its centre as functions of slope height, cohesion, internal friction angle, and water-related conditions. The method is supported by long-term field observations and geotechnical investigations of clay slopes, including dry and water-affected scenarios. Two representative stability conditions are considered: dry slopes and slopes influenced by an elevated depression curve. The method was evaluated for 45° clay slopes with heights up to 60 m, using eight representative cases: four dry scenarios and four water-affected scenarios. The calculated factors of safety were compared with GEO5 SLOPE results obtained using Bishop’s simplified method. The comparison showed that most analysed cases presented differences below 5% between the proposed express method and the Bishop-based numerical benchmark, with larger deviations occurring only in selected boundary cases. The results demonstrate that the proposed method can provide a rapid preliminary assessment of clay slope stability, supporting early-stage geotechnical diagnosis, risk screening, and decision-making in regions where clayey formations and slope instability are recurrent. Full article

During the operation of large reservoirs, slope rock masses at different elevations are subjected to confining pressure variation and alternating wet–dry cycles induced by water-level fluctuations, resulting in the evolution of their mechanical properties. To investigate this issue, conventional triaxial compression tests were conducted on limestone from Badong County in the Three Gorges Reservoir area under confining pressures of 5–20 MPa and 0–50 wet–dry cycles. The results show that confining pressure significantly enhances limestone strength, whereas wet–dry cycles induce a progressive deterioration in mechanical properties. Under the same confining pressure, the deterioration exhibits a staged characteristic, with a rapid decrease at the early stage followed by a slower decline. Higher confining pressure effectively suppresses crack propagation and mitigates the degradation caused by wet–dry cycling. Meanwhile, wet–dry cycles promote the transition of the failure mode from single-fracture failure to multi-fracture fragmentation. The elastic modulus, cohesion, and internal friction angle all decrease exponentially with increasing wet–dry cycles. Based on damage mechanics theory, a constitutive relationship considering wet–dry cycle effects was established to characterize rock stiffness degradation and its influence on the overall mechanical response. The proposed model effectively describes the evolution of mechanical parameters and deformation characteristics under wet–dry cycling conditions. This study provides an experimental and theoretical basis for evaluating the long-term stability of reservoir slopes. Full article

Fruit color is a key quality trait in cherry tomato (Solanum lycopersicum) and an important factor influencing consumer purchasing decisions. Various pigments, including flavonoids, carotenoids, and chlorophylls, form the biochemical basis of fruit coloration, imparting vivid colors such as red, yellow, orange, and green. Flavonoids and carotenoids are also essential nutritional components in cherry tomato, directly influencing their commercial value, while chlorophylls are crucial for photosynthesis and fruit development. However, conventional tomato varieties typically contain insufficient flavonoid levels to meet human dietary requirements. In this study, we quantified flavonoids, carotenoids, and chlorophyll a and b in ten high-flavonoid cherry tomato cultivars and investigated the relationships between fruit color and pigment content. The results revealed that red and orange tomato varieties contained higher flavonoid and carotenoid levels than yellow varieties, while green tomatoes exhibited elevated chlorophyll content. Yellow varieties showed the maximum L* (lightness) value. Flavonoid and carotenoid contents were significantly positively correlated with a* (red-green axis) and a*/b* (yellow-blue axis) values but negatively correlated with hue angle, whereas chlorophyll content showed no significant correlations with color parameters. Our findings provide guidance for evaluating the nutritional value of cherry tomatoes based on pigmentation. Full article

To address the insufficient representation of terrain constraints and surface resistance in traditional path planning for off-road environments, this study proposes an improved A* path planning method for unmanned ground vehicles. First, an off-road environment model is constructed using Digital Elevation Model (DEM) and land cover data, and environment–vehicle traversability is evaluated by integrating geometric and support-based traversability analyses. Geometric constraints are determined using slope thresholds, minimum ground clearance, and approach/departure angles, while support-based traversability is quantified through a surface velocity influence coefficient to reflect traversal-efficiency differences under various surface conditions. These terrain and surface constraints are incorporated into the actual cost function of the A* algorithm, and a direction-corrected heuristic function is designed to enhance goal-directed search. Experiments conducted in Jiancaoping District, Taiyuan, show that, compared with the traditional A* algorithm, the proposed method reduces cumulative travel time, maximum path slope, and expanded nodes by 15.3%, 22.9%, and 47.8%, respectively, with only a 2.4% increase in path length. The results demonstrate that the proposed method effectively avoids steep and high-resistance areas while achieving coordinated optimization of path length, traversal efficiency, and terrain safety. Full article

To address the challenge of achieving a unified dynamic evaluation of in-service performance for reflector antennas subjected to coupled wind disturbances, structural flexibility, and servo control, an end-to-end performance evaluation method based on integrated modeling is proposed. A disturbance–structure–electromagnetic–control integrated modeling framework is constructed, in which the fluctuating wind load, structural dynamics model, cascaded servo control, and end-to-end performance mapping model are unified within a state-space closed-loop system, thereby enabling time-domain dynamic evaluation from environmental excitation inputs to performance index outputs. The Davenport spectrum and harmonic superposition method are adopted to establish a stochastic fluctuating wind model, and structural disturbance inputs are formed through wind pressure linearisation and modal projection. A low-order flexible dynamic model of the reflector antenna is developed using finite element modal condensation, and a main-axis closed-loop control model is formulated by incorporating fuzzy active disturbance rejection control and notch filtering. By combining the best-fit parabolic surface, the weighted half-path-length difference, and the Ruze formula, an end-to-end mapping model that relates structural nodal displacements to electromagnetic performance degradation is established. The research demonstrates that the proposed method can effectively reveal the influence of wind speed, elevation angle, and flexible mode coupling on antenna performance. Furthermore, a performance evaluation system developed based on this method integrates parameter input, simulation computation, and result output, providing an effective tool for antenna design optimization and performance assurance. Full article

Regenerated cellulose is a promising tribopositive material for sustainable triboelectric nanogenerators (TENGs), although its electrical output remains sensitive to surface and interfacial properties. In this study, regenerated cellulose was modified using atomic layer deposition (ALD) of Al₂O₃, TiO₂, and ZnO to investigate how nanoscale oxide coatings influence triboelectric performance against a tribonegative PTFE counter layer. Two deposition regimes were examined: 7 ALD cycles, representing the early stage of ALD growth, and 200 cycles, representing a more developed coating regime. Triboelectric measurements, dielectric spectroscopy, structural characterization and contact angle analysis, were used to evaluate how ALD modification influences the electrical response of regenerated cellulose. All ALD-modified samples exhibited increased surface charge density and power output compared to unmodified cellulose, while also showing improved retention of triboelectric performance at elevated relative humidity. The 7-cycle samples consistently outperformed the corresponding 200-cycle coatings under low-humidity conditions, whereas the 200-cycle ZnO sample exhibited the highest humidity stability. No direct correlation between wettability and triboelectric output was observed. The results suggest that relatively small interfacial modifications introduced by ALD are sufficient to influence both the triboelectric response and humidity-dependent charge dissipation behavior of regenerated cellulose. Full article

Water channel experiments were conducted to investigate the influence of aspect ratio (H/D = 0.9–1.9) on the flow-induced motion (FIM) and hydrokinetic energy conversion performance of an elastically mounted circular cylinder with T-shaped attachments (Cir-T-Att). The results indicate that the aspect ratio critically governs the vortex-induced vibration (VIV) to galloping transition by modulating the effective angle of attack. While larger H/D promotes galloping and higher amplitudes under low damping, this benefit is negated under elevated system damping, where amplitudes are uniformly suppressed. Consequently, the maximum power output exhibits a non-monotonic dependence with H/D. Within the investigated parametric range, peak performance occurs at H/D = 1.1, with a total damping ratio ζ_total = 0.122 and reduced velocity U_r = 11.25. For practical harvester design, the optimal H/D should be selected by aligning the intended oscillation regime with local flow characteristics. Full article

Reliable prediction of post-initiation run-out distance of rainfall-induced landslides is essential for hazard assessment, evacuation planning, and disaster-risk mitigation. However, most existing data-driven approaches formulate run-out prediction as a deterministic regression problem and therefore provide limited information on predictive uncertainty, rare long-runout events, and explainable decision support. To address these limitations, this study proposes CQR-EVT-XAI, a trustworthy AI framework that integrates Quantile LightGBM, Conformalized Quantile Regression (CQR), Extreme Value Theory (EVT), and Explainable Artificial Intelligence (XAI) for uncertainty-aware and explainable landslide run-out risk prediction. Based on 10,158 rainfall-induced landslide samples, physics-informed features are constructed from elevation difference H, source area A, source volume V, and mean slope angle $\theta$. The proposed framework generates calibrated prediction intervals, threshold-based exceedance probabilities, upper-tail risk indicators, and interpretable risk levels. The CQR-LightGBM median model achieves high point-prediction accuracy, with $R^2$ = 0.939, RMSE = 18.03 m, and MAE = 6.55 m. Conformal calibration improves the empirical coverage of the nominal 90% and 95% prediction intervals from 0.813 to 0.903 and from 0.876 to 0.953, respectively. Tail-risk analysis shows that the upper prediction bound ${\widehat{L}}_{95}$ effectively identifies extreme long-runout events, achieving recall values of 0.974 and 0.900 for L > 300 m and L > 500 m, respectively. SHAP analysis reveals that elevation difference H, source volume V, and energy-related derived features dominate both median run-out prediction and upper-tail risk behavior, while slope-related variables mainly influence predictive uncertainty and exceedance-risk levels. These results demonstrate that the proposed CQR-EVT-XAI framework provides a practical workflow for calibrated uncertainty quantification, tail-risk identification, and explainable decision support in rainfall-induced landslide run-out risk assessment. Full article

The intertidal beach profile provides a fundamental representation of beach morphology and serves as a key indicator of shoreline morphodynamics. To enable frequent and accurate mapping of intertidal beach profiles, this study proposes an automated reconstruction framework that integrates single-pixel image columns with a stacked bidirectional long short-term memory (Bi-LSTM) network. Time-exposure imagery, commonly referred to as Timex imagery, acquired from a shore-based video monitoring station at Xisha Bay, China, is used as the primary data source, while wave records obtained from a wave buoy are incorporated to assign elevations to the detected waterline breakpoints, thereby enabling automatic beach profile reconstruction. The stacked Bi-LSTM network is trained for land–sea segmentation and waterline breakpoint localization. achieving the best performance among the tested methods, with precision, recall, accuracy, and F1 score values of 0.951, 0.894, 0.978, and 0.903, respectively, and a mean breakpoint localization error of 2.23 pixels. Breakpoint elevations were then estimated using a local slope–wave setup attribution model. Validation against field-measured topographic data from four fixed profiles and three survey periods showed good agreement between the reconstructed and measured profiles, with a period-based root mean square error (RMSE) of 0.212 ± 0.080 m. When all validation points were combined, the reconstructed elevations showed strong agreement with the measured elevations, with a coefficient of determination (R²) of 0.988 and an overall RMSE of 0.24 m. The profile comparisons further showed that the reconstructed profiles generally captured the overall profile shape and cross-shore morphological pattern of the measured profiles, although reconstruction accuracy varied among the four fixed profiles. These differences demonstrate that camera viewing angle, field-of-view position, camera-to-profile distance, and image quality are important factors influencing video-derived beach profile reconstruction. These results indicate that the proposed method can directly reconstruct fixed intertidal beach profiles from shore-based Timex imagery without generating a digital elevation model of the entire intertidal zone. It provides a practical tool for high-frequency monitoring of intertidal profile morphology and supports the quantitative analysis of beach erosion–accretion dynamics. Full article

The influence of tempering temperature within the range of 520 °C to 640 °C on the microstructure and mechanical properties of 04Cr13Ni5Mo maraging stainless steel was systematically studied. The evolution of crystallographic orientation information, such as phase ratio and grain boundary ratio of the studied steel at different tempering temperatures, was studied by utilizing the electron backscatter diffraction (EBSD) technique. Furthermore, the element distribution at typical tempering temperatures was quantitatively analyzed by utilizing the electron probe microanalysis (EPMA) technique. Results indicated that the microstructure of the studied steel at different tempering temperatures is mainly composed of tempered sorbite. As the tempering temperature increased from 520 °C to 640 °C, the proportion of low-angle grain boundaries gradually increased while the proportion of large-angle grain boundaries decreased. The content of reversed austenite showed a sharp increase with the elevation of tempering temperature and peaked at approximately 9.0% at a tempering temperature of 640 °C. With the tempering temperature increasing from 520 °C to 640 °C, the strength of the studied steel showed a trend of first decreasing, then stabilizing, and then decreasing again, while the plasticity showed a stable upward trend. When the tempering temperature was 610 °C, the strength, plasticity, and toughness of the studied steel achieved the optimal match. The enrichment of the Ni element during the austenite reverse phase transformation process was confirmed as the predominant factor ensuring the stability of the reverse austenite to room temperature. Full article

To investigate the influence of isolation-layer eccentricity on the torsional response of step-terrace mountain (STM) structures, a 1:10 scaled reinforced concrete model was designed and tested using shaking table experiments. Both isolated and non-isolated configurations were considered, and different eccentricity levels were achieved by adjusting the bearing layouts in the upper and lower isolation layers. The torsional response was evaluated in terms of torsional angle, torsional displacement ratio, and relative torsional effect. The results indicate that the non-isolated STM structure exhibits pronounced torsional amplification and progressive damage accumulation. Deformation and damage are concentrated in the upper stories and dropped-story region, eventually leading to a stiffness–degradation–dominated failure pattern. In contrast, the STM isolated structure effectively suppresses torsional response, and inter-story rotations remain small and relatively uniform along the height, indicating that seismic deformation is primarily redistributed within the isolation layers rather than amplified in the superstructure. The experimental results further demonstrate that torsional behavior is governed by the coupling effect between isolation-layer eccentricity and seismic input direction. The eccentricity in the upper isolation layer plays the dominant role in triggering torsional amplification, while simultaneous eccentricities in both isolation layers produce a cumulative torsional effect. When the eccentricity of the isolation layers is controlled within 5%, the torsional displacement ratio remains below 1.2, while the non-isolated structure reaches values exceeding the code limit of 1.5. In addition, slope-direction excitation intensifies absolute torsional deformation due to overturning effects induced by elevation differences. These findings highlight that torsional response in STM isolated systems is controlled by the interaction between vertical irregularity and isolation-system asymmetry. Full article