Search Results (2,428)

Deep foundation excavation in water-rich sand strata presents complex deformation characteristics driven by fluid–solid interaction, which distinguishes it from excavations in cohesive soft clay. This study investigates the spatiotemporal evolution and deformation mechanisms of retaining structures through a comparative analysis of field monitoring data and 3D numerical simulation, based on a subway station project in Xi’an. While the numerical simulation predicted a continuous “bulging” deformation mode, field monitoring revealed a distinct transition from a “bulging” profile to a “step-like” deformation pattern as the excavation deepened. Quantitatively, while the simulation captured the spatial trend, the measured maximum surface settlement (7.8 mm) exceeded the simulated value (1.2 mm), highlighting the dominant role of seepage consolidation. Detailed analysis indicates that this discrepancy—and the unique step-like evolution—is primarily driven by two mechanisms: the rapid stress relaxation of cohesionless sand during the time lag of support installation, and the superimposed seepage forces induced by continuous dewatering, which are often simplified in standard elastoplastic models. The study further identifies that the vertical displacement of the pile top is governed by the combined effects of basal heave and the “kick-out” deformation at the pile toe. These findings demonstrate that in high-permeability water-rich sand, deformation control depends critically on minimizing the unsupported exposure time of the excavation face. This research provides a theoretical basis for optimizing the spatiotemporal sequencing of excavation in similar geological conditions. Full article

The depletion of fossil fuel resources and the growing need for sustainable energy solutions have increased interest in vertical axis wind turbines (VAWTs), which offer advantages in urban and variable-wind environments but often exhibit limited performance at low tip speed ratios (TSRs). This study optimizes VAWT aerodynamic behavior across a wide TSR range by varying three geometric parameters: maximum thickness position ($a/b$), relative thickness (m), and pitch angle ($\beta$). A two-dimensional computational fluid dynamics (CFD) framework, combined with the Metamodel of Optimal Prognosis (MOP), was used to build surrogate models, perform sensitivity analyses, and identify optimal profiles through gradient-based optimization of the integrated $C_p$–$\lambda$ curve. The Joukowsky transformation was employed for efficient geometric parameterization while maintaining aerodynamic adaptability. The optimized airfoils consistently outperformed the baseline NACA 0021, yielding up to a 14.4% improvement at $\lambda =2.64$ and an average increase of 10.7% across all evaluated TSRs. Flow-field analysis confirmed reduced separation, smoother pressure gradients, and enhanced torque generation. Overall, the proposed methodology provides a robust and computationally efficient framework for multi-TSR optimization, integrating Joukowsky-based parameterization with surrogate modeling to improve VAWT performance under diverse operating conditions. Full article

A novel multi-wavelength differential absorption lidar operating at 1.5 μm band is proposed and theoretically analyzed for simultaneous remote sensing of vertical profiles of H₂¹⁶O, HD¹⁶O, and the isotopic ratio δD. The spectral band is compatible with mature, commercially available fiber-optic components, ensuring practical implementability. By employing the 1976 U.S. Standard atmosphere and considering the temperature dependence of H₂¹⁶O, the systematic error induced by a +1 K temperature uncertainty within the 2 km altitude is limited to 0.81% through appropriate absorption line selection. Simulations of atmospheric backscattered signals with a time resolution of 30 min and a range resolution of 120 m show that random error remains below 0.16% up to 2 km. The simultaneous retrieval errors of H₂¹⁶O and HD¹⁶O mixing ratio profiles at 2 km are 0.13 g/kg (3.19%) and 1.69 × 10⁻⁴ g/kg (18.02%), respectively, from which the δD is successfully and reliably retrieved. The results provide essential technical guidance for implementing high-resolution, isotopologue-resolved lidar observations in atmospheric science. Full article

The analysis of ground-penetrating radar data generally relies on the visual identification of structures on selected profiles and their interpretation in terms of buried features. In simple cases, inverse modelling of the acquired data set can facilitate interpretation and reduce subjectivity. These methods suffer from severe restrictions due to antenna resolution limits, which prevent the identification of tiny structures, particularly in forensic, stratigraphic, and engineering applications. Here, we describe a technique to obtain a high-resolution characterization of the underground, based on the forward modelling of individual traces (A-scans) of selected radar profiles. The model traces are built by superposition of Ricker wavelets with different polarities, amplitudes, and arrival times and are used to create reflectivity diagrams that plot reflection amplitudes and polarities versus depth. A thin bed is defined as a layer of higher or lower permittivity relative to the surrounding material, such that the top and bottom reflections are subject to constructive interference, determining the formation of an anomalous peak in the trace (tuning effect). The proposed method allows the detection of ultra-thin layers, well beyond the Rayleigh vertical resolution of GPR antennas. This approach requires a preliminary estimation of the instrumental uncertainty of common monostatic antennas and takes into account the frequency-dependent attenuation, which causes a spectral shift of the dominant frequency acquired by the receiver antenna. Such a quantitative approach to analyzing radar data can be used in several applications, notably in stratigraphic, forensic, paleontological, civil engineering, heritage protection, and soil stratigraphy applications. Full article

Limnological parameters were monitored in four highland reservoirs in the Czech Republic from 2022 to 2024 to evaluate the effects of management practices on water quality. Although the reservoirs share similar morphometry and all serve as drinking water sources, they differ in trophic status and management: Hubenov (HU, eutrophic) is stocked with piscivores, Nová Říše (NŘ, mesotrophic) undergoes hypolimnetic aeration, and Landštejn (LA, meso-oligotrophic) and Mostiště (MO, eutrophic) receive no targeted management interventions. Limnological data were collected monthly from April to October along vertical profiles in dam parts of the reservoirs. Comparisons were performed using graphical presentation and linear mixed-effects models. Analyses of abiotic (thermal, oxygen, and pH stratification, transparency, total phosphorus (TP) and nitrogen (TN) concentrations) and biotic (algae chlorophyll-a, cyanobacterial pigments, zooplankton density and composition) variables revealed that HU and MO exhibited the lowest transparency (on average 1.9 m in both in contrast to 2.2 m and 2.8 m in NŘ and LA, respectively) and highest seasonal algae chlorophyll-a concentrations (11.4 µg/L in HU and 15.1 µg/L in MO in contrast to 6.4 µg/L in NŘ and 5.5 µg/L in LA), indicating negligible improvement from biomanipulation. In contrast, NŘ demonstrated nutrient and chlorophyll-a levels comparable to LA (TP: 0.010 mg/L and 0.009 mg/L, TN: 1.591 mg/L and 0.419 mg/L, in NŘ and LA, respectively), despite higher nutrient input, and achieved the second highest transparency. Zooplankton densities were similar across reservoirs, supporting the hypothesis of bottom-up control or insufficient piscivore impact. These findings highlight the importance of reducing nutrient inputs to preserve water quality. Hypolimnetic aeration, which enhances sediment nutrient retention, appears more effective at mitigating eutrophication and controlling algal proliferation than fish stocking, a commonly applied biomanipulation approach. Full article

Magnetorheological fluids (MRFs) exhibit dynamic, field-responsive mechanical properties, as they form chain-like and networked microstructures under magnetic stimuli. This study numerically investigates the structural and mechanical behavior of three-dimensional (3D) microbead chain assemblies, focusing on cubic and hexagonal body-centered tetragonal (BCT) configurations formed under compressive and magnetic field-driven aggregation. A finite element-based model simulates magnetostatic and stress evolution in solidified structures composed of up to 20 particle chains. The analysis evaluates magnetic flux distribution, total magnetic force, and time-resolved stress profiles under vertical loading. Results show that increasing chain density significantly enhances magnetic coupling and reduces peak stress, especially in hexagonal lattices, where early stress equilibration and superior lateral load distribution are observed. The hexagonal BCT structure exhibits superior resilience, lower stress concentrations, and faster dissipation under dynamic loads. These findings offer insights into designing energy-absorbing MRF-based materials for impact mitigation, adaptive damping, and protective microfluidic structures. Full article

Olive mill wastewater (OMW) contains high organic loads and phytotoxic polyphenols. In Tunisia, OMW is often stored in unlined evaporation ponds. This practice creates a risk of soil and groundwater contamination. This study evaluates the environmental impact of a long-term OMW evaporation pond in the Ben Aoun area, Sidi Bouzid region. The investigation combines wastewater, soil and groundwater sampling with laboratory physicochemical analyses. Three OMW samples (E1 surface, E2 mixed, E3 recent spill) were collected. Three shallow boreholes (0–5 m) were sampled at 20 cm intervals. In addition, three nearby pumping wells were sampled. All samples were analyzed for pH, electrical conductivity (EC), chemical oxygen demand (COD), total and volatile solids, major cations/anions, total nitrogen, total phosphorus and total polyphenols. Results obtained using the Folin–Ciocalteu method are expressed as mg Eq AG L⁻¹ for liquids and mg Eq AG gMS⁻¹ for soils. OMW samples showed high COD (E1 = 48, E2 = 70, E3 = 80 g/L) and polyphenols (E1 = 5, E2 = 9.7, E3 = 14 g/L). Soil profiles inside the pond exhibited increased EC with peak of 15.48 mS cm⁻¹ at 0.4 m depth. Near-surface layers showed low pH and increased organic matter and polyphenols to depths of ~5 m. Groundwater samples collected near the pond contained measurable polyphenols (up to 41 mg/L in the closest well), indicating subsurface migration. Evidence indicates lateral migration of about 20 m and vertical infiltration to a depth of approximately 5 m beneath the pond. The findings demonstrate that unlined OMW evaporation ponds act as a persistent source of organic and phenolic contamination. This poses a potential risk to shallow groundwater. Full article

Mpox is an emerging zoonotic infection caused by the Monkeypox virus, an Orthopoxvirus with increasing global relevance following the 2022 multinational outbreak. Historically endemic to Central and West Africa, the disease has evolved from sporadic zoonotic transmission to sustained human-to-human spread, particularly through close physical and intimate contact. Clinical manifestations typically include fever, lymphadenopathy, and progressive mucocutaneous lesions, although severity varies according to viral clade, immune status, and comorbidities. The 2022 outbreak, predominantly associated with the Clade IIb variant, was characterized by milder disease, localized lesions, and reduced mortality compared with the more virulent Clade I variant. Despite this, severe outcomes remain possible, particularly in vulnerable groups such as children, pregnant individuals, immunocompromised patients, and persons with extensive dermatological disorders. Diagnosis relies primarily on polymerase chain reaction testing from lesion-derived samples, with genomic sequencing serving as a complementary tool for epidemiological surveillance. Management is largely supportive, though antivirals such as tecovirimat may be considered in severe cases or in high-risk populations. Data regarding therapeutic safety in pregnancy are limited; however, tecovirimat appears to have the most favorable profile, whereas cidofovir and brincidofovir remain contraindicated. Prevention strategies include targeted vaccination with the non-replicating Modified Vaccinia Ankara–Bavarian Nordic vaccine, used for both pre- and post-exposure prophylaxis, particularly in individuals at elevated risk. Given the evolving epidemiological profile, the potential for vertical transmission, and the risk of adverse perinatal outcomes, Mpox infection during pregnancy poses unique clinical challenges. This review synthesizes current evidence on virology, clinical presentation, diagnosis, prevention, and management, with an emphasis on obstetric considerations and public health implications. Full article

Current studies on large-span structural components have largely emphasized flexural performance, whereas multi-ribbed profiled steel sheeting-concrete composite slabs may be prone to inclined-section shear failure in the construction stage, particularly at small shear-span ratios. To ensure that the vertical shear capacity of such composite slabs satisfies construction-stage requirements, a numerical model validated against experimental evidence was employed. A systematic parametric study was conducted to clarify the influence of key structural parameters and the shear-span ratio on the vertical shear resistance. On this basis, a calculation method for the vertical shear capacity was proposed based on the strength-equivalence principle and verified against numerical results. The results indicate that the inclined-section shear failure of multi-ribbed profiled steel sheeting-concrete composite slabs develops through four characteristic stages, the shear-span ratio governs the transition of failure mode, and slabs with a rib height of h = 150 mm exhibit a pronounced shear-dominated failure when the shear-span ratio is less than 2. Increasing the rib inclination angle degrades the composite interaction between the profiled steel sheeting and concrete, whereas increasing the sheeting thickness and slab depth enhances the load-bearing capacity and stiffness, and longitudinal reinforcement benefits the internal stress redistribution of concrete. A vertical shear capacity model was formulated for the novel multi-ribbed profiled steel-concrete composite slab and verified against numerical results. The research helps to bridge the gap in studies on the vertical shear performance of multi-ribbed profiled steel-concrete composite slabs and offers design guidance for vertical shear checks of composite slabs in the temporary construction stage. Full article

Saline water intrusion poses a major threat to groundwater security in arid and semi-arid regions, reducing freshwater availability and challenging sustainable water resource management. Accurate delineation of the fresh-saline water interface is therefore essential; however, conventional hydrochemical and laboratory-based assessments remain costly, invasive, and spatially limited. Resistivity methods have long been used to infer subsurface salinity, as low resistivity typically reflects clay-rich saline water and higher resistivity reflects freshwater-bearing sand or gravel. Yet, resistivity values for similar lithologies frequently overlap, causing ambiguity in distinguishing fresh and saline aquifers. To overcome this limitation, Dar–Zarrouk (D–Z) parameters are often applied to enhance hydrogeophysical discrimination, but previous studies have relied exclusively on one-dimensional (1D) D–Z derivations using vertical electrical sounding (VES), which cannot resolve the lateral complexity of alluvial aquifers. This study presents the first application of electrical resistivity tomography (ERT) to derive two- and three-dimensional D–Z parameters for detailed mapping of the fresh-saline water interface in the alluvial aquifers of Punjab, Pakistan. ERT provides non-invasive, continuous, and high-resolution subsurface imaging, enabling volumetric assessment of aquifer electrical properties and salinity structure. The resulting 2D/3D models reveal the geometry, depth, and spatial continuity of salinity transitions with far greater clarity than VES-based or purely hydrochemical methods. Physicochemical analyses from boreholes along the ERT profiles independently verify the geophysical interpretations. The findings demonstrate that ERT-derived 2D/3D D–Z modeling offers a cost-effective, scalable, and significantly more accurate framework for assessing fresh-saline water boundaries. This approach provides a transformative pathway for sustainable groundwater monitoring, improved well siting, and long-term aquifer protection in salinity-stressed alluvial regions. Full article

Lake Batur, located within a volcanic caldera in Bali, Indonesia, is subjected to anthropogenic pressures related to agriculture, aquaculture, tourism, and religious activities, which may affect its water quality and ecology condition. This study investigates the physicochemical properties of lake water and diatom assemblages preserved in lake sediments to provide insight into environmental conditions in this volcanic alkaline ecosystem. Water quality parameters, including pH, temperature, electrical conductivity (EC), and total dissolved solids (TDS), were measured. Vertical profiles of temperature and conductivity revealed stable stratification, with minimal variation below 20 m water depth. Elevated nitrogen concentrations, including nitrate (NO₃⁻), nitrite (NO₂⁻), and ammonium (NH₄⁺), were observed, particularly in the southern basin, suggesting localized nutrient enrichment. Scanning electron microscopy (SEM) analysis of lake sediment samples identified ten diatom genera, including Ulnaria, Denticula, and Discostella, which are commonly associated with nutrient-enriched freshwater environments. Overall, the results indicate that Lake Batur exhibits conditions consistent with early-stage eutrophication in localized areas, highlighting the importance of continuous monitoring and targeted management strategies to protect the ecological integrity of this volcanic lake system. Full article

Long-term human cultivation activities are the key factors of the vertical distribution and storage dynamics of soil organic carbon (SOC) in cropland. Based on a 45-year long-term field experiment, this study systematically compared SOC dynamics and carbon storage characteristics in soil profiles (0–200 cm) between cultivated land and adjacent natural forest. The findings reveal the hierarchical regulatory effects of tillage management on the soil carbon pool. The results show that: (1) Under both land use types, SOC content decreased exponentially with depth, but values in cultivated soils were 0.35–1.54% lower than in forest soils at each layer. SOC content in surface soil (0–78 cm) was significantly higher than in the subsoil (78–158 cm) and substratum layers (158–200 cm) (p < 0.01). At equivalent depths, SOC in cultivated land was significantly lower than in forest land (p < 0.01). Over 45 years, the SOC accumulation rate in the surface soil of cropland (0.07 g·kg⁻¹·yr⁻¹) was only half that of forest land (0.14 g·kg⁻¹·yr⁻¹). (2) The controls of soil physicochemical properties on SOC differed with land use: in forest soils, SOC correlated positively with clay content (r = 0.63, p < 0.01), whereas in cultivated soils, SOC was primarily regulated by total nitrogen (r = 0.94, p < 0.01) and sand content (r = 0.60, p < 0.01) and negatively correlated with bulk density (r = −0.55, p < 0.01) and pH value (r = −0.45, p < 0.05). (3) Long-term tillage significantly reshaped soil profile structure, thickening the plough layer from 20 cm to 78 cm. Surface carbon storage reached 20.76 t·ha⁻², an increase of 11.13 t·ha⁻² compared with forest soil (p < 0.01). However, storage decreased by 4.99 t·ha⁻² and 7.60 t·ha⁻² in the subsoil and substratum layers, respectively (p < 0.01). The SOC storage increment rate was 50.95 t·ha⁻²·yr⁻¹ higher than that of forest soil in the surface layer but 46.81 t·ha⁻²·yr⁻¹ and 11.12 t·ha⁻²·yr⁻¹ lower in deeper layers. These results confirm that cultivation alters soil structure and material cycling, enhancing carbon enrichment in surface soils while accelerating depletion of deeper carbon pools. This provides new insights into the vertical differentiation mechanisms of SOC under long-term agricultural management. Full article

This study examines how varying the isolated pea protein (IPP) levels (0, 10, 20, 30, 40, 50%) together with key extrusion conditions, including moisture level, barrel heating profile, and screw rotation speed, affect the physicochemical attributes and textural characteristics of high-moisture meat analogs (HMMAs). Results indicated that increased IPP content reduced the fiber structure, springiness, cohesiveness, chewiness, cutting strength, and integrity index of HMMAs. Processing conditions resulted in pronounced changes in both the physicochemical attributes and texture of HMMAs. The increase in moisture content resulted in a decrease in HMMA fiber structure and textural properties. In contrast, increases in barrel temperature and screw speed were associated with higher TPA values, greater cutting strength in both vertical and parallel orientations, and an improved integrity index in HMMAs. Furthermore, the gelation behavior of IPP played a critical role in the formation of the fibrous structure, with optimal gel strength and water retention achieved under specific extrusion conditions. These findings underscore the importance of protein gelation in structuring IPP-based meat analogs and provide insights into the gel-based mechanisms underlying their textural properties. Overall, the optimum IPP content to produce HMMAs in this experiment was 30%, and the process variables were 55% moisture content, barrel temperature of 160 °C, and screw speed of 250 rpm. Full article

In this paper, a simple method of estimating reference optical turbulence profiles at the Huairou Solar Observing Station (HSOS) from a large meteorological dataset is used. These reference profiles can be used in simulations of atmospheric variability above the station and the impact of climate change on image quality. By analyzing the statistics of measured optical turbulence and using the ERA-5 reanalysis data, vertical distributions of optical turbulence above HSOS were obtained for different time periods (1940–1969, 1970–1999, 1989–2010, 2000–2025). It has been shown that the intensity of optical turbulence in the surface layer has been decreasing in recent decades, while the intensity in the upper troposphere has a tendency to increase. Trends are also assessed in total cloud cover and atmospheric boundary layer height at the HSOS site. Observed changes are associated with global warming. Full article

The planetary boundary layer (PBL) exerts strong control on heat, moisture, and momentum exchange, yet its representation over the steep mountains and deep valleys of Liangshan remains poorly understood. This study evaluates six Weather Research and Forecasting (WRF) PBL schemes (ACM2, BL, MYJ, MYNN2.5, QNSE, and YSU) using multi-source observations from radiosondes, surface stations, and wind profiling radar during clear-sky dry-season cases in spring and winter. The schemes exhibit substantial differences in governing turbulent mixing and stratification. For the specific cases studied, QNSE best reproduces 2 m temperature in both seasons by realistically capturing nocturnal stability and large diurnal ranges, while non-local schemes overestimate nighttime temperatures due to excessive mixing. MYNN2.5 performs robustly for boundary layer growth in spring, and BL aligns most closely with radar-derived PBL height (PBLH). Vertical profile comparisons show that QNSE and MYJ better represent the lower–middle level thermodynamic structure, whereas all schemes underestimate extreme near-surface winds, reflecting unresolved terrain-induced variability. PBLH simulations reproduce diurnal cycles but differ in amplitude, with QNSE occasionally producing unrealistic spikes. Overall, no scheme performs optimally for all variables. However, QNSE and MYNN2.5 show the most balanced performance across seasons. These findings provide guidance for selecting PBL schemes for high-resolution modeling and fire–weather applications over complex terrain. Full article