Search Results (3,715)

The functional performance and structural integrity of natural rock materials under fluctuating environmental stressors are pivotal for their advanced applications. As a non-ionizing and radiation-free technology, terahertz (THz) spectroscopy offers a safe and promising alternative for non-destructive testing (NDT), uniquely capable of being deployed in open and unshielded environments. However, limited penetration depth, exacerbated by both the dense geological matrix and the extreme sensitivity of THz waves to moisture states, has long hindered its widespread application in rock characterization. This study establishes a quantitative Terahertz Time-Domain Spectroscopy (THz-TDS) framework to characterize four lithologies under drying–wetting cycles. Exponential signal attenuation across thicknesses was quantified based on the Beer–Lambert law, with attenuation coefficients ranging from 0.15 to 0.74 per millimeter. Planar transmission imaging successfully visualizes lithologic and moisture-dependent heterogeneity: limestone exhibits a dense, homogeneous structure with stable amplitude distribution; sandstone and purple sandstone show parallel statistical trends, reflecting uniform pore networks; and granite demonstrates the most pronounced imaging contrast under varying moisture states, driven by complex grain-boundary scattering. The findings reveal that THz transmission is dictated by the synergistic effects of mineral compositions and pore structures: scattering at grain boundaries and fractures leads to significant energy dissipation, whereas clay-rich lithologies exhibit the highest sensitivity to moisture variations due to water adsorption and interfacial polarization effects. As an exploration of THz technology in the non-destructive evaluation of rock materials, these findings establish an analytical framework for the quantitative assessment of microstructure evolution. Full article

In the field of subgrade compaction quality assessment, accurate volume measurement of excavated pits is hindered by non-uniform point cloud distribution, environmental noise interference, and complex irregular boundary features. To address these challenges, this paper proposes a robust volume detection framework that integrates adaptive point cloud refinement and morphological discrimination. First, a pose normalization method employing RANSAC plane fitting and rigid body transformation corrects the spatial orientation of the raw point clouds. To balance data redundancy removal with feature preservation, a gradient adaptive simplification strategy based on local density feedback and K-nearest neighbor estimation is developed. Subsequently, a cross-sectional area calculation model utilizing piecewise-cubic polynomial fitting is proposed to mitigate boundary noise and accurately reconstruct irregular contours. Furthermore, a dynamic outlier removal mechanism based on the Median Absolute Deviation (MAD) and sliding windows is introduced to eliminate non-physical geometric fluctuations. Finally, the total volume is aggregated using a hybrid strategy of Simpson’s rule and a frustum compensation operator. Experimental results on simulated pits with typical topological defects demonstrate that the proposed algorithm outperforms traditional methods, achieving an average relative volume error of less than 0.8%. This approach significantly improves the robustness and precision of sensor-based automated subgrade compaction quality measurement. Full article

Sustainable management of peatlands is one of the key global strategies for mitigating climate change. The balance between carbon (C) sequestration and emission in peatlands reflects environmental conditions over time and can provide insight into long-term ecosystem dynamics. However, current methods for estimating greenhouse gas (GHG) fluxes are often labor-intensive, costly, and site-specific. In this study, we propose a simplified and cost-efficient method to estimate long-term carbon balance in peatlands based on the inorganic (mineral) content of drill core samples. The approach uses exponential decay equations to approximate peat accumulation and decomposition processes over time. A conceptual model is applied that accounts for both anaerobic transformation of organic matter of varying molecular complexity and enhanced aerobic decomposition resulting from anthropogenic drainage during the last century. The model was applied to more than 100 drill cores from four peatland systems in Estonia. The resulting trends were compared qualitatively with known climatic fluctuations of the last millennium, including periods associated with the Little Ice Age. The results suggest that, in many cases, carbon losses from decomposition in deeper peat layers may exceed carbon accumulation in upper layers, even in peatlands that appear to be well preserved. The proposed method provides a rapid, low-cost, first-order approximation of peatland carbon dynamics and may serve as a complementary tool for large-scale assessments where detailed process-based models are not feasible. Full article

Cities are artificial ecosystems that suffer most from environmental issues and climate change. Urban Heat Island (UHI) effects represent an increasing challenge, especially for compact Mediterranean cities characterized by high population density and extensive impervious surfaces. This study assessed localized microclimatic conditions within the small Maltese coastal town of Isla through a 15-day summer field monitoring campaign. Air temperature, relative humidity, and wind speed were measured across urban locations characterized by different levels of vegetation coverage and thermal vulnerability. The analysis combined descriptive statistics, Mann–Whitney U testing, and Multiple Linear Regression (MLR) models. In addition, site-specific Nature-based Solutions (NbS) scenarios were proposed as context-sensitive strategies to support urban heat mitigation and climate resilience. The results highlighted distinct microclimatic responses between the sites investigated. In particular, the MLR analysis suggested that non-vegetated areas were more sensitive to short-term atmospheric variability associated with wind speed and relative humidity fluctuations. These findings suggest that urban vegetation may contribute not only to localized cooling, but also to increased microclimatic stability within compact Mediterranean urban environments. Full article

Soil salinization is one of the most severe forms of land degradation in arid and semi-arid regions, posing substantial threats to agroecosystem stability and food security. In this study, saline–alkali soil collected from the Wuding River Basin in Yulin, Shaanxi Province was used to construct a three-factor amendment system comprising superabsorbent polymers (SAP), biochar, and humic acid. A systematic assessment was conducted to elucidate their combined effects on soil water–salt transport and crop growth. Results from one-dimensional constant-head infiltration experiments using indoor soil columns demonstrated that the application of amendments significantly increased cumulative infiltration and improved the uniformity of wetting-front advancement. Specifically, the treatments regulated the redistribution of salts within the soil profile; while surface salinity reduction varied, the leaching efficiency was significantly enhanced in the A2B2C2 treatment. Soil bulk density (BD) showed dynamic fluctuations during the growth cycle, peaking at 1.628 cm⁻³ during the branching stage, while high-rate biochar (A3) reduced BD by up to 13.64% compared to the control by the initial flowering stage. Fitting results based on the Philip and Kostiakov models further indicated that the combined amendment strategy—particularly the A2B2C2 treatment (30 kg/ha SAP, 15,000 kg/ha biochar, and 600 kg/ha humic acid)—markedly enhanced both the initial infiltration rate and the steady infiltration capacity. Field experiments corroborated the indoor findings: plant height and dry biomass of Melilotus officinalis (L.)Lam. were significantly higher under amendment treatments than in the control, driven by improved water availability, mitigated salt stress, and enhanced soil structure. Single-factor and multi-factor interaction analyses revealed that SAP exerted pronounced effects during early growth stages, whereas biochar and humic acid contributed more substantially during the middle to late stages through sustained regulatory functions. Collectively, the results demonstrate that the combined application of SAP, biochar, and humic acid improves the water–salt regime of saline–alkali soils through a coupled “water–salt–structure–plant” mechanism, ultimately enhancing crop productivity. This study provides both theoretical insights and practical guidance for the amelioration of saline–alkali soils. Full article

Lipizzan horses, bred for over four centuries, represent a unique genetic, cultural and historic resource. This study assessed genetic diversity and population structure across seven European Lipizzan populations, with emphasis on the Bosnia and Herzegovina population. A total of 547 Lipizzan horses were genotyped using 12 microsatellite markers. The parameters of genetic variability, admixture level and migration rate were calculated. The mean number of alleles, effective number of alleles and Shannon’s information index were 5.78, 3.24 and 1.31, respectively. The average fixation indices were estimated to be F_IT = 0.05 (SE = 0.02), F_IS = −0.02 (SE = 0.01), and F_ST = 0.07 (SE = 0.01). The level of genetic diversity observed within each Lipizzan horse subpopulation shows similar fluctuations, with the lowest values observed in Bosnia and Herzegovina and the highest in the Slovak Lipizzan population. The observed heterozygosity was lower than the expected heterozygosity. The Hardy–Weinberg equilibrium was maintained in Serbia, while minor deviations occurred in other populations, most notably in Slovakia. Nei’s genetic distances were highest between Slovakia and other populations, particularly Bosnia and Herzegovina. The population structure analysis confirmed admixture involving Bosnia and Herzegovina, and the migration pattern corresponded to geographic proximity and breeding practices. These findings provide a valuable basis for developing breeding strategies to reduce inbreeding and preserve genetic diversity. Full article

Large portions of rural population in South Africa lack access to basic water and sanitation. This advocates for urgent interventions in support of water supply. This study assessed the performance of solar-powered groundwater pumping systems established at nine pilot sites in rural areas of Greater Giyani Municipality (Limpopo, South Africa). Performance assessment indicators, namely weather, groundwater abstraction, power supply, water supply, water quality, number of beneficiaries and farm productivity, were monitored (2023–2024). Increased groundwater abstraction reduced groundwater levels by 0.4–11 m, depending on the monitored borehole. This was replenished by above-average rainfall in 2023 (≈650 mm). Power supply and pump discharge rates were stable with generally low fluctuations at recommended pumping rates (0.5–2.0 L s⁻¹). Groundwater quality was generally fit to marginal for irrigation and drinking. High levels of NO₃⁻ and total organic carbon, especially in the proximity of villages, mandated the installation of mini water treatment plants for drinking water. The implementation of solar-powered groundwater pumping schemes was generally successful, with more than 5000 villagers benefiting directly from the interventions, whilst smallholder farms turned into commercial and financially viable enterprises. Long-term monitoring of bio-physical and socio-economic drivers is essential to ensure long-term sustainability of the solar-powered groundwater pumping systems. Full article

The fuel and operation efficiency of combustion engines and power plants as a whole depends essentially on the in-cycle air temperature and drops when the temperature increases. Thermally stabilized, fuel-efficient engine operation at lower air temperatures is possible due to cooling. This can be conducted by heat recovery chillers (HRC) consuming the heat removed from the engine. Such combined production of power, heat, and refrigeration, applied for cooling engine in-cycle air, is considered to be a promising trend in integrated energy systems (IES) and energetics as a whole. The in-cycle trigeneration ensures a sustainable, thermally stabilized, and highly fuel-efficient operation of power plants. Starting from the strong influence of cyclic air temperature, the rate of in-cycle air cooling is considered as the rate of engine thermal stabilization (RS) and calculated as a ratio of the real drop in cyclic air temperatures to their target values when cooling air to the desired temperatures. Such a novel approach allows for assessing the effectiveness of cooling air issuing based on both aspects: fuel efficiency and engine thermal stabilization quantitatively by RS as a unified primary criterion indicator to synthesize a cooling system with heightened RS. A case study of an IES with in-cycle trigeneration confirmed that the developed an innovative gas engine cyclic air cooling system provided increased annual average weighted values of RS_avr of about 0.44 with an enlarged duration of engine thermally stabilized operation against 0.24 for a basic typical system. Furthermore, the engine’s thermally stabilized operation due to in-cycle air cooling ensures minimum thermal load fluctuations, caused by air temperature variation. As a result, the concept of sustainable fuel-efficient operation of IES due to in-cycle air cooling and the general approaches, hypotheses, and criteria at its core have been developed. Full article

Aerosol optical depth (AOD) and Ångström exponent (AE) are critical parameters for characterizing atmospheric aerosols, playing a pivotal role in atmospheric environmental monitoring and climate change studies. This study addressed the imperative need for a systematic evaluation of mainstream reanalysis products by conducting a comprehensive multi-scale assessment of the CAMS and MERRA-2 datasets (2003–2023), encompassing data quality verification, spatiotemporal pattern analysis, and trend evolution investigation. The following key findings emerge: (1) Both AOD data exhibited the best performance observed in low–mid latitudes. CAMS AOD (AODC) showed a slightly better correlation, while MERRA-2 AOD (AODM) demonstrated superior robustness. Both AE data performed similarly, and MERRA-2 AE (AEM) was superior. Both AE data performed better in low latitudes and near Europe. (2) CAMS and MERRA-2 showed good performance in annual and seasonal variations, with significant fluctuations and biases in the annual cycle. Both models achieved the highest AE performance in summer. MERRA-2 AOD demonstrated better hourly performance during daytime. The hourly stability of AE was slightly worse than AOD, with notably degraded performance during midday hours. (3) The distribution and trends of AOD over land showed spatial consistency. The distribution of AEM was generally lower than AEC’s. After ensemble empirical mode decomposition (EEMD), all datasets showed monotonically decreasing trends except for AEM. This study provides valuable insights into the strengths and limitations for CAMS and MERRA-2 and suggests possible areas for improvement in future data assimilation and parameterization. Full article

Assessing electricity market efficiency is important for power market reform and the development of sustainable power systems. Efficient prices can improve resource allocation and provide better signals for system operation, system flexibility and low-carbon transition. Against this background, this study examines the efficiency of three representative provincial electricity spot markets in China, Shandong, Shanxi and Guangdong, using day-ahead and real-time price data from January 2022 to August 2024. A multi-method framework including unit root tests, price convergence tests, detrended fluctuation analysis and sample entropy is employed to evaluate market efficiency and compare differences across provinces. The results show that none of the three markets satisfies the weak-form Efficient Market Hypothesis. The fractal analysis and entropy results further suggest that market efficiency remains limited. Cross-provincial differences are nevertheless observed, which may be partly related to intraday load patterns, generation mix, market structure, and market design. This study provides useful evidence for deepening electricity market reform, as well as promoting the efficient and sustainable development of power systems. Full article

Remaining Useful Life (RUL) forecasting models are essential to enable predictive maintenance strategies. However, selecting the most appropriate model based solely on conventional accuracy metrics may be insufficient for practical decision making, where an adequate prediction horizon is required to plan maintenance activities. This study investigates the impact of prediction horizon on model performance and its implications for maintenance decision making. A multi-horizon evaluation approach is applied to assess model accuracy across different predictive horizons. The results show the fluctuation of accuracy and prediction error over different prediction horizons. Across both datasets, predictive accuracy was generally lowest at the long horizon (11.64–86.62%), remained variable at the medium horizon (18.13–82.04%), and was highest at the short horizon (30.29–98.25%). The results demonstrate that model performance varies significantly with the prediction horizon, highlighting a trade-off between prediction accuracy and the time available for operational planning. These findings emphasize that models with high short-term accuracy may not necessarily support effective maintenance decisions if sufficient lead time is not provided. The findings show how prediction horizon considerations shall be integrated into a risk-based evaluation framework, in which model performance is interpreted in relation to the operational consequences of prediction errors. A complete risk-based predictive maintenance framework is proposed to support a shift toward comprehensive, risk-based evaluation as a prerequisite for reliable and effective RUL prediction in predictive maintenance systems. Full article

Financial market development is an inherently multidimensional construct shaped by institutional, legal, market-based, and macro-financial conditions, and therefore cannot be adequately captured through single-indicator proxies. To address this complexity, this research proposes an integrated hybrid multi-criteria decision-making methodology, namely the CRISUS (CRiterion Importance based on the SUm of Squares)-LODECI (LOgarithmic DEcomposition of Criteria Importance)-WENSLO (Weights by ENvelope and SLOpe)- ARTASI (Alternative Ranking Technique based on Adaptive Standardized Intervals) framework, to comparatively assess the financial market development performance of twenty-six African economies. The evaluation structure is grounded in six criteria derived from the Absa Africa Financial Markets Index, with decision matrix values computed as arithmetic averages over the 2022–2025 period to capture persistent structural characteristics rather than cyclical fluctuations. The three weighting procedures, each operating on mathematically distinct information extraction principles, are linearly integrated to yield a composite criterion weight vector that is robust to method-specific distributional assumptions. The resulting weights identify pension fund development, legal standards and enforceability, and market depth as the dominant criteria, collectively accounting for the preponderance of cross-country performance variation. ARTASI rankings place South Africa, Mauritius, and Namibia at the top of the performance distribution, while Madagascar, DRC, and Ethiopia occupy the lowest positions. Sensitivity analysis under alternative weighting parameterizations and benchmarking against seven established MCDM methods confirm the stability and convergent validity of the proposed framework. Full article

Macrozoobenthic communities function as important bioindicators of natural and anthropogenic pressures in transitional ecosystems and contribute to ecosystem processes. Transitional systems, such as lagoons, estuaries and coastal ponds, exhibit strong physico-chemical variability, often intensified by anthropogenic pressures and climate change. Changes in macrozoobenthic communities across five Veneto Po Delta lagoons were assessed through long-term monitoring (2008–2025) conducted within the Water Framework Directive and additional monitoring activities. The macrozoobenthic communities were analysed to assess temporal variability and inter-lagoon differences in the Po Delta system; ecological indices were generally stable, but organism density showed significant interannual fluctuations, with marked declines in 2008, 2009, 2024, and 2025. Univariate and multivariate analyses identified phases of community restructuring driven by temporal shifts in species composition and relative abundance. These patterns may reflect the interacting effects of multiple stressors, including long-term anthropogenic pressures and the recent expansion of the invasive blue crab Callinectes sapidus, although causality was not assessed. Increases in water temperature and suspended solids were observed across all lagoons, potentially affecting benthic communities. Overall, this study provides an assessment of macrozoobenthic variability and a preliminary analysis of the factors that may have influenced it, highlighting patterns that warrant further investigations to elucidate the underlying mechanisms. Full article

Riverine detritus is a key nutritional resource for benthic consumers, yet its biochemical quality fluctuates rapidly and is poorly captured by bulk indicators such as elemental analysis. To improve assessment sensitivity, we compared two analytical approaches targeting organic nitrogen. We refined a fluorimetric assay for primary amines using o-phthalaldehyde (OPA), identifying 2 M KCl as an optimal extraction medium that maximizes recovery while minimizing matrix interference. In parallel, we optimized capillary electrophoresis with contactless conductivity detection (CE-C4D) for free amino acid determination using 0.4 M ammonium carbonate. Applied to detritus from multiple river sites and seasons, both methods showed that primary amines and amino acids vary by an order of magnitude more than total nitrogen and exhibit patterns not detectable by elemental analysis, with consistent temporal trends across catchments. Primary amine-based measurements therefore provide a more sensitive and ecologically relevant assessment of detrital nutritional quality than bulk nitrogen metrics. The OPA assay is well suited for routine monitoring due to its simplicity and robustness, whereas CE-C4D enables detailed compositional profiling where amino acid speciation is required. Overall, detrital quality reflects both intrinsic properties and recent hydrological conditions, underscoring the importance of antecedent discharge and precipitation dynamics in its interpretation. Full article

To investigate the impacts of tidal level fluctuations on the groundwater dynamics and stability of coastal slopes, a numerical simulation framework was developed using the SEEP/W and SLOPE/W modules in GeoStudio. By combining saturated–unsaturated seepage mechanics with the finite element limit equilibrium method, the semi-diurnal tidal cycle was simulated to derive analytical solutions for the internal water-level distribution within the slope, and to assess the factor of safety as well as the geometry of the potential slip surface. By examining the evolutionary patterns of the phreatic surface and pore-water pressure inside the slope, this work elucidates the failure mechanisms of coastal slopes under tidal forcing. The findings demonstrate that tidal fluctuations induce periodic, hysteretic variations in the slope’s phreatic surface, which peaks at the conclusion of the rising tide (t = 0 h) and reaches its trough at the end of the falling tide (t = 6 h). Pore-water pressure alterations are predominantly localized in the near-surface region of the slope. The slope’s factor of safety exhibits pronounced oscillations in tandem with tidal levels, attaining a maximum at the end of the rising tide (t = 0 h) and a minimum at the end of the falling tide (t = 6 h), thus identifying the falling tide phase as the critical window for instability. Tidal changes exert a comparatively limited influence on the spatial positioning of the slip surface, underscoring the concealed and abrupt nature of tidal impacts on slope stability. Numerical simulation outcomes align closely with theoretical calculations, with small relative errors, which verifies the consistency and effectiveness of the simulation and theoretical calculations. Full article