Search Results (209)

Additive manufacturing (AM), particularly laser powder bed fusion (L-PBF), provides unmatched design flexibility for creating intricate steel structures with minimal post-processing. However, adopting L-PBF for high-performance applications is difficult due to the challenge of predicting microstructure evolution. This is because the process is sensitive to many parameters and has a complex thermal history. Thin-walled geometries present an added challenge because their dimensions often approach the scale of individual grains. Thus, microstructure becomes a critical factor in the overall integrity of the component. This study focuses on applying cellular automata (CA) modeling to establish robust and efficient process–structure relationships in L-PBF of 316L stainless steel. The CA framework simulates solidification-driven grain evolution and texture development across various processing conditions. Model predictions are evaluated against experimental electron backscatter diffraction (EBSD) data, with additional quantitative comparisons based on texture and morphology metrics. The results demonstrate that CA simulations calibrated with relevant process parameters can effectively reproduce key microstructural features, including grain size distributions, aspect ratios, and texture components, observed in thin-walled L-PBF structures. This work highlights the strengths and limitations of CA-based modeling and supports its role in reliably designing and optimizing complex L-PBF components. Full article

The lower sub-member of Member 2, Dongying Formation (Paleogene) in the HHK Depression hosts an extensively developed thin-bedded beach-bar system characterized by favorable source rock conditions and reservoir properties, indicating significant hydrocarbon exploration potential. Integrating drilling cores, wireline log interpretations, three-dimensional seismic data, geochemical analyses, and palynological data, this study investigates the sedimentary characteristics, sandbody distribution patterns, controlling factors, and genetic model of this lacustrine beach-bar system. Results reveal the following: (1) widespread thin-bedded beach-bar sandbodies dominated by fine-grained sandstones and siltstones, exhibiting wave ripples and low-angle cross-bedding; (2) two vertical stacking patterns, Type A, thick mudstone intervals intercalated with laterally continuous thin sandstone layers, and Type B, composite sandstones comprising thick sandstone units overlain by thin sandstone beds, both demonstrating significant lateral continuity; (3) three identified microfacies: bar-core, beach-core, and beach-margin facies; (4) key controls on sandbody development: paleoenvironmental evolution establishing the depositional framework, secondary fluctuations modulating depositional processes, strike-slip extensional tectonics governing structural zonation, paleobathymetry variations and paleotopography controlling distribution loci, and provenance clastic influx regulating scale and enrichment (confirmed by detrital zircon U-Pb dating documenting a dual provenance system). Collectively, these findings establish a sedimentary model for a thin-bedded beach-bar system under the strike-slip extensional tectonic framework. Full article

Malaria remains a major public health issue, especially near hydroelectric dams that often promote mosquito breeding. This study aimed to establish baseline epidemiological data during the construction of the Singrobo–Ahouaty dam to support assessment and decision-making for short- and long-term health impacts on surrounding communities. A cross-sectional survey was carried out in randomly selected households. Blood samples were analyzed using thick/thin smears and rapid diagnostic tests, while sociodemographic and behavioral data were collected via questionnaires. Statistical analyses included chi-square, Mann–Whitney, Kruskal–Wallis tests, and logistic regression. The malaria prevalence was 43.1% (394/915). The parasite density averaged 405.7 parasites/µL. School-age children (6–13 years) showed the highest prevalence (74.3%, p < 0.0001), while younger children (0–5 years) had the highest parasite density (1218.0 parasites/µL, p < 0.0001). Highly elevated infection rates (>51%) occurred in Sokrogbo, N’Dènou, and Amani-Menou, with the highest density in Ahérémou 1 (5663.9 parasites/µL). Risk factors included being an informal worker (ORa = 1.5), working in the raw material sector (ORa = 1.4) or market gardening/rice farming (ORa = 0.9; p = 0.043), and frequent mosquito bites (OR = 0.4; p = 0.017). These results underscore the need for stronger vector control strategies, improved bed net distribution and follow-up, and enhanced intersectoral collaboration in dam-influenced areas to reduce malaria transmission. Full article

The longstanding debate over early hominin subsistence strategies, particularly the hunting-versus-scavenging hypothesis, as well as discussions regarding the functionality of Oldowan sites, has been primarily centered on the archeological and paleoanthropological record of Olduvai Gorge. Historically, FLK Zinj has been at the core of these debates, serving as a principal empirical reference due to the prevailing assumption that most other Bed I sites at Olduvai represented non-anthropogenic accumulations However, recent discoveries have significantly reshaped this perspective. Newly identified early sites, including PTK, DS, and AGS, situated within the paleolandscape and thin stratigraphic context of FLK Zinj, provide crucial new anthropogenic datasets. These sites offer additional dimensions to the study of early hominin behavior, facilitating a more nuanced reconstruction of their adaptive strategies in this paleoenvironment. Furthermore, methodological advancements in recent years—including controlled experimental and actualistic studies, sophisticated statistical modeling, and the integration of machine learning algorithms—have greatly enhanced the analytical frameworks available for investigating early hominin behavior. These innovations have refined the ability to formulate and test hypotheses within a rigorous scientific paradigm, significantly improving the resolution of archeological and taphonomic interpretations. This study presents an in-depth taphonomic analysis of the faunal assemblage from level 22A at DS, a Bed I site at Olduvai Gorge dated to approximately 1.84 Ma. The assemblage exhibits exceptional preservation, enabling detailed assessments of skeletal part representation, fragmentation patterns, and surface modifications. By combining traditional taphonomic methodologies with state-of-the-art AI-driven bone surface modification (BSM) analyses, this research contributes novel insights into the interactions between early hominins and carnivores, elucidating the complex ecological dynamics of an Early Pleistocene African paleolandscape. Full article

Laser powder-bed fusion (L-PBF) additive manufacturing has been widely explored for fabricating intricate metallic parts such as lattice structures with thin struts. However, L-PBF-fabricated small parts (e.g., thin struts) exhibit different morphological and mechanical characteristics compared to bulk-sized parts due to distinct scan lengths, affecting the melt pool behavior between transient and quasi-steady states. This study investigates the keyhole porosity in Ti6Al4V thin struts fabricated by L-PBF, incorporating a range of strut sizes, along with various levels of linear energy densities. Micro-scaled computed tomography and image analysis were employed for porosity measurements and evaluations. Generally, keyhole porosity lessens with decreasing energy density, though with varying patterns across a higher energy density range. Keyhole porosity in struts predictably becomes severe at high laser powers and/or low scan speeds. However, a major finding reveals that the porosity is reduced with decreasing strut size (if less than 1.25 mm diameter), plausibly because the keyhole formed has not reached a stable state to produce pores in a permanent way. This implies that a higher linear energy density, greater than commonly formulated in making bulk components, could be utilized in making small-scale features to ensure not only full melting but also minimum keyhole porosity. Full article

This investigation presents the current status of seismic sedimentology, along with seismic geomorphology, as applied to the high-resolution (<5 m) mapping of sedimentary facies and hydrocarbon reservoirs in the subsurface. Seismic sedimentology involves the joint investigation of seismic lithology and seismic geomorphology. The high-resolution (as thin as one meter) interpretation of depositional units on lithofacies and paleo-landforms can be achieved by following a comprehensive workflow focusing on three mandatory steps (evaluating and improving data quality; selecting right attributes, preferably 90° seismic trace with frequency fusion; and making use of horizontal resolution on stratal slices) and two optional steps (guiding interpretation with seismic models and applying machine learning techniques). Seismic sedimentology is set to improve through enhanced calibration using well and outcrop data, along with regional and local geological models. Furthermore, there will be a deeper integration between geological and geophysical disciplines, as well as advancements in high-resolution geophysical acquisition and processing techniques. Full article

This study investigates the challenges and opportunities associated with improving the vertical resolution of normal and lateral resistivity logs in thin-bedded rock formations. The proposed iterative inversion procedure combines a finite element method forward modeling procedure with a particle swarm optimization algorithm to generate high-resolution models of the rock formation. The performance of the inversion approach was evaluated using synthetic datasets, and the results of the inversion of field data from thin-bedded formations of the Polish Carpathians are presented. This research highlights the potential of modern computational techniques to enhance the utility of historical resistivity logging data in current studies. Full article

The South China Block hosts extensive sedimentary phosphorites that offer valuable insights into both paleoenvironmental reconstruction and rare earth element (REE) resource potential. However, the mechanisms governing REE enrichment in these deposits remain poorly understood. This study investigates two distinct phosphorite layers from the Lower Cambrian Zhujiaqing (ZJQ) Formation in the Bailongtan (BLT) area of the Yangtze Platform using integrated analyses including petrology, XRD, major and trace elements, δ¹³C and δ¹⁸O isotopes, and LA-ICP-MS. The lower thin-bedded phosphorite, composed of finer phosphatic grains (<300 μm), exhibits significantly higher REE concentrations (883.6 ± 160.9 ppm; n = 48) compared to the upper thick-bedded phosphorite (303.2 ± 82.7 ppm; n = 64), which is dominated by larger, reworked grains (300–600 μm). Intervening strata consist of laminated phosphate-bearing carbonates interbedded with quartz, dolomite, and pyrite. PAAS-normalized REE patterns display MREE–HREE enrichment, negative Ce anomalies (avg. 0.60 ± 0.18; n = 18), and positive Y anomalies—indicative of oxic depositional conditions. The elevated REE content in the lower layer, coupled with the lowest δ¹³C values (−4.59‰), suggests enrichment linked to organic matter degradation. A proposed two-stage depositional model links REE enrichment to proximity with REE-rich deep-shelf waters, underscoring the critical role of redox and depositional dynamics in phosphorite-hosted REE accumulation. Full article

During the development of coal resources in China, mine bed-separation water damage has become a new type of disaster in recent years, bringing severe casualties and economic losses to mining areas. This study aims to solve the limitations of the existing bed-separation calculation methods. It proposes a new method of bed-separation discrimination based on the bending deflection of rock strata and a spatial volumetric calculation model that considers the development stage of bed separation. The improved stepwise comparison combination method (ISCCM) was combined with the theory of thin elastic plates to determine the developmental stage of the bed separation, which was able to predict the location of the bed separation and its volume more accurately. An example analysis of the 21301 working face in Cui mu Coal Mine, Shaanxi Province, shows that the proposed method exhibits higher accuracy and reliability in predicting the location of bed-separation development and the water inrush risk. The study shows that changes in the morphology of bed-separation development significantly affect the amount of water accumulation, and the traditional calculation method may produce a significant error after long-distance coal mining. This research result helps to improve the early warning ability and management effect of water damage in the mine bed separation. It provides technical support for the safe and efficient production of the mine. Full article

Thin-bedded beach-bar reservoirs in the continental faulted basins of eastern China hold significant potential, yet pose challenges for unconventional hydrocarbon development due to their thin-layer characteristics and heterogeneity. This study focuses on the Paleogene Lower E₃d₂ Sub-member in the HHK Depression, Bohai Bay Basin as a case study. We propose an innovative technical framework integrating Self-Organizing Map (SOM) multi-attribute optimization with seismic waveform inversion. Petrophysical analysis demonstrates that waveform-indicated inversion can detect 1.8–3.0 m thin sandstones, achieving a 90.2% mean match rate (95% CI: 87.5–92.7%, n = 12; bootstrap resampling) for training wells and 81.5% (95% CI: 76.8–85.3%, n = 11) for validation wells. By integrating SOM seismic attribute clustering with seismic waveform inversion, we were able to delineate microfacies boundaries with precision, enhancing the visibility of beach-bar sand body distributions. This methodology establishes a new paradigm for thin-bed sandstone prediction in low-well-control areas, providing critical support for geological interpretation and resource evaluation in complex depositional systems. Full article

The Permian Lucaogou Formation (PLF) shale oil reservoirs in the Junggar Basin exhibit significant lithological heterogeneity, which limits the understanding of the relationship between macroscopic and microscopic reservoir characteristics, as well as insights into reservoir quality. To address this gap, thirty core samples, exhibiting typical sedimentary features, were selected from a 46 m section of the PLF for sedimentological analysis, thin section examination, high-performance microarea scanning, and scanning electron microscopy. Seven main lithofacies were identified, including massive bedding slitstone/fine-grained sandstone (LS1), cross to parallel bedding siltstone (LS2), climbing ripple laminated argillaceous siltstone (LS3), paired graded bedding argillaceous siltstone (LS4), irregular laminated argillaceous siltstone (LS5), irregular laminated silty mudstone (LM2), and horizontal laminated mudstone (LM2). The paired graded bedding sequences with internal erosion surfaces, massive bedding, and terrestrial plant fragments suggest a lacustrine hyperpycnal flow origin. The channel subfacies of hyperpycnal flow deposits, primarily consisting of LS1 and LS2, reflect strong hydrodynamic conditions, with a single-layer thickness ranging from 1.3 to 3.8 m (averaging 2.2 m) and porosity between 7.8 and 14.2% (averaging 12.5%), representing the primary sweet spot. The lobe subfacies, composed mainly of LS3, LS4, and LS5, reflect relatively strong hydrodynamic conditions, with a single-layer thickness ranging from 0.5 to 1.4 m (averaging 0.8 m) and porosity between 4.2 and 13.8% (averaging 9.6%), representing the secondary sweet spot. In conclusion, strong hydrodynamic conditions and depositional microfacies are key factors in the formation and distribution of sweet spots. The findings of this study are valuable for identifying sweet spots in the PLF and provide useful guidance for the exploration of lacustrine shale oil reservoirs in the context of hyperpycnal flow deposition globally. Full article

The sandstone sections in the Upper Jurassic red beds of the Yongjin area in the central Junggar Basin are important oil and gas reservoirs. The debate over whether red beds are of primary depositional or secondary diagenetic origin persists, leading to uncertainties in the interpretation of reservoir sedimentary facies. This study uses core samples and employs thin section microscope observations, scanning electron microscopy, X-ray diffraction, and major and trace element analyses to investigate the formation period and paleoclimate conditions of red beds and explore the origin of red sandstone. The Upper Jurassic red beds are mainly deposited in arid delta plain environments. The framework grains of the red sandstone are composed of quartz (averaging 22.6%), feldspar (averaging 16.3%), and rock fragments (averaging 36.7%). The rock fragments in the sandstone are mainly composed of intermediate basic volcanic rocks and cryptocrystalline acid volcanic rocks, which are rich in mafic silicate minerals such as olivine, pyroxene, ilmenite, and magnetite. In situ hematitization of ilmenite is observed in the rock fragments, suggesting that the in situ alteration of mafic silicate minerals in the parent rock is the main source of iron ions for hematite. Tiny hematite crystals (2.1 μm) are observed in clay mineral micropores via SEM. Abundant mixed-layer illite/smectite clay indicates early smectite transformation, providing a minor source of iron ions for hematite. Hematite in the red sandstone occurs as a grain-coating type, predating quartz overgrowth, feldspar overgrowth, and (ferroan) calcite and (ferroan) dolomite precipitation. Residual hematite coatings between detrital grain point contacts indicate that hematite is a product of syn-sedimentary or very early diagenetic precipitation, ruling out the possibility that red sandstone formation was caused by later atmospheric water leaching during the fold and thrust belt stage. The average chemical index of alteration (CIA) for the red sandstone is 52.2, whereas the CIA for the red mudstone averages 59.5, and the chemical index of weathering (CIW) reached a maximum of 69. These values indicate that the rocks have undergone mild chemical weathering in arid climates. Additionally, the ratios of trace elements indicate that the water bodies were in an oxidizing state during the sedimentary period. The arid climate and oxidative water conditions were ideal for hematite preservation, thus facilitating red bed formation. The red bed sediments in the study area represent a direct response to the Late Jurassic aridification event and can be compared to global climate change. The results have important implications for stratigraphic correlation and interpretation of reservoir sedimentary facies in the study area while also providing a valuable case study for global research on red beds. Full article

This publication presents the results of research on selected quality features of sample models made using 3D printing technology from the Powder Bed Fusion (PBF) group and a material based on aluminum powder. Two quality areas were analyzed: tensile strength and geometric surface structure. Strength tests of thin-walled models were carried out for samples with four given thicknesses of 1, 1.4, 1.8, and 2 mm and four printing directions, namely, three in the XZ plane and one in the XY plane. The measurement of the geometric structure was carried out using optical measuring devices and by taking into account the assessment of roughness and waviness parameters. Using scanning electron microscopy (SEM), an analysis of the fracture of samples after rupture was carried out and the surface was assessed for technological defects created in the manufacturing process. The test results showed that for thin-walled sample models, there are certain technological limitations regarding the minimum sample thickness in the manufacturing process and that the strength of thin-walled models in relation to “solid” samples depends on both the sample thickness and the printing direction. Roughness parameters that determine functional quality characteristics such as friction and wear were determined and also showed a dependence on the printing direction. Full article

The widespread occurrence of encapsulated phase change materials (PCMs) within a mineral matrix has been demonstrated to improve the thermo-physical properties of final products. The upscaling of such materials has not yet been achieved, as traditional onsite mixing and casting processes could damage the capsule, leading to a leakage of the active content and then a deterioration of the final element. The aim of this paper is to evaluate the influence of selectively depositing a layer of PCM on plaster, through a powder bed 3D printing process, on its density and thermal conductivity. A home-made selective-binding 3D printer has been used to assess samples of composites of calcium sulfate and encapsulated PCM. Thermal conductivity and Scanning Electron Microscope measurements were carried out on pure calcium sulfate as well as on a mix design containing a 5% mass ratio of PCM. The SEM measurements highlight that the PCM shells are undamaged by the selective-binding 3D printing process compared to the traditional mixing and casting process. Also, the 3D-printed composite material demonstrates a thermal conductivity reduction of 39%, which is linked to the 17% decrease in density. This applicative study validates the idea of designing functionally composite construction materials with phase change materials inserted as a thin layer between printed plaster layers and also demonstrates the great potential of this innovative selective-binding 3D printing technique. Full article

The aim of this research was to recognize the role of landslides and lithology in determining the within-year variability of stream runoff in small forested catchments. The research was conducted in 2022 in three areas located in the Outer Carpathians (Poland). In each of three areas, two small catchments were selected: a catchment with landslides and a control catchment. The presence of landslides increases the within-year variability of stream runoff: the degree of increase depends on the lithology of the catchment and the properties of landslides. These two factors determine the water storage capacity of the catchments. The greatest variability in stream runoff occurs in the catchment where impermeable shale dominates in lithology and landslides are numerous but relatively small. Smaller differences occur in the catchment mainly formed of thin-bedded sandstone, where there is one medium-sized landslide covering about 30% of the catchment area. The smallest differences occur in the catchment formed mainly of thick-bedded sandstone, where the entire landslide catchment is found within one large landslide. The size of landslides determines their depth, and consequently, the depth of landslide fissures: the deeper the system of landslide fissures, the longer the water transit time, and the greater the catchment storage capacity. Full article