Search Results (547)

The Surface Water and Ocean Topography (SWOT) mission provides unprecedented high-resolution observations of sea-surface height. However, their direct use in ocean circulation studies is complicated by the presence of small-scale unbalanced motion signals and instrumental noise, which hinder accurate estimation of geostrophic velocities. To address these limitations, we developed an adaptive convolutional neural network (CNN)-based filtering technique that refines SWOT-derived sea-level observations. The network includes multi-head attention layers to exploit information on concurrent wind fields and standard altimetry interpolation errors. We train the model with a custom loss function that accounts for the differences between geostrophic velocities computed from SWOT sea-surface topography and simultaneous in-situ drifter velocities. We compare our method to existing filtering techniques, including a U-Net-based model and a variational noise-reduction filter. Our adaptive-filtering CNN produces accurate velocity estimates while preserving small-scale features and achieving a substantial noise reduction in the spectral domain. By combining satellite and in-situ data with machine learning, this work demonstrates the potential of an adaptive CNN-based filtering approach to enhance the accuracy and reliability of SWOT-derived sea-level and velocity estimates, providing a valuable tool for global oceanographic applications. Full article

The applicability of the in-situ pyrolysis of oil-rich coal is highly dependent on regional geological conditions. In this study, six major geological factors and 19 key parameters influencing the in-situ pyrolysis of oil-rich coal were systematically identified. An analytic hierarchy process incorporating index classification and quantification was employed in combination with the geological features of the Tiaohu mining area to establish a feasibility evaluation index system suitable for in-situ development in the study region. Among these factors, coal quality parameters (e.g., coal type, moisture content, volatile matter, ash yield), coal seam occurrence characteristics (e.g., seam thickness, burial depth, interburden frequency), and hydrogeological conditions (e.g., relative water inflow) primarily govern pyrolysis process stability. Surrounding rock properties (e.g., roof/floor lithology) and structural features (e.g., fault proximity) directly impact pyrolysis furnace sealing integrity, while environmental geological factors (e.g., hazardous element content in coal) determine environmental risk control effectiveness. Based on actual geological data from the Tiaohu mining area, the comprehensive weight of each index was determined. After calculation, the southwestern, central, and southeastern subregions of the mining area were identified as favorable zones for pyrolysis development. A constraint condition analysis was then conducted, accompanied by a one-vote veto index system, in which the thresholds were defined for coal seam thickness (≥1.5 m), burial depth (≥500 m), thickness variation coefficient (≤15%), fault proximity (≥200 m), tar yield (≥7%), high-pressure permeability (≥10 mD), and high-pressure porosity (≥15%). Following the exclusion of unqualified boreholes, three target zones for pyrolysis furnace deployment were ultimately selected. Full article

The Advanced Scatterometer (ASCAT), Soil Moisture Active Passive (SMAP), and European Space Agency-Climate Change Initiative (ESA–CCI) soil moisture (SM) products are widely used in agricultural drought monitoring, water resource management, and climate analysis applications. However, the performance of these SM products varies significantly across regions and environmental conditions, due to in sensor characteristics, retrieval algorithms, and the lack of localized calibration. This study proposes a multi-source long short-term memory (MLSTM) for improving ASCAT, ESA–CCI, and SMAP SM products by combining in-situ SM measurements and four key auxiliary variables: precipitation (PRE), land surface temperature (LST), fractional vegetation cover (FVC), and evapotranspiration (ET). First, the in-situ measured data from four in-situ observation networks were corrected using the LSTM method to match the grid sizes of ASCAT (0.1°), ESA–CCI (0.25°), and SMAP (0.1°) SM products. The RPE, LST, FVC, and ET were used as inputs to the LSTM to obtain loss data against in-situ SM measurements. Second, the ASCAT, ESA–CCI, and SMAP SM datasets were used as inputs to the LSTM to generate loss data, which were subsequently corrected using LSTM-derived loss data based on in-situ SM measurements. When the mean squared error (MSE) loss values were minimized, the improvement for ASCAT, ESA–CCI, and SMAP products was considered the best. Finally, the improved ASCAT, ESA–CCI, and SMAP were produced and evaluated by the correlation coefficient (R), root mean square error (RMSE), and standard deviation (SD). The results showed that the RMSE values of the improved ASCAT, ESA–CCI, and SMAP products against the corrected in-situ SM data in the OZNET network were lower, i.e., 0.014 cm³/cm³, 0.019 cm³/cm³, and 0.034 cm³/cm³, respectively. Compared with the ESA–CCI and SMAP products, the ASCAT product was greatly improved, e.g., in the SNOTEL network, the Root Mean-Square Deviation (RMSD) values of 0.1049 cm³/cm³ (ASCAT) and 0.0662 cm³/cm³ (improved ASCAT). Overall, the MLSTM-based algorithm has the potential to improve the global satellite SM product. Full article

Ru/TiO₂ catalysts are well known for their high activity in the hydrogenation of CO₂ to CH₄ (the Sabatier reaction). This activity is commonly attributed to strong metal–support interactions (SMSIs), associated with reducible oxide layers partly covering the Ru-metal particles. Moreover, isothermal rates of formation of CH₄ can be significantly enhanced by the exposure of Ru/TiO₂ to light of UV/visible wavelengths, even at relatively low intensities. In this study, we confirm the significant enhancement in the rate of formation of methane in the conversion of CO₂, e.g., at 200 °C from ~1.2 mol g_Ru⁻¹·h⁻¹ to ~1.8 mol g_Ru⁻¹·h⁻¹ by UV/Vis illumination of a hydrogen-treated Ru/TiO_x catalyst. The activation energy does not change upon illumination—the rate enhancement coincides with a temperature increase of approximately 10 °C in steady state (flow) conditions. In-situ DRIFT experiments, performed in batch mode, demonstrate that the Ru–CO absorption frequency is shifted and the intensity reduced by combined UV/Vis illumination in the temperature range of 200–350 °C, which is more significant than can be explained by temperature enhancement alone. Moreover, exposing the catalyst to either UV (predominantly exciting TiO₂) or visible illumination (exclusively exciting Ru) at small intensities leads to very similar effects on Ru–CO IR intensities, formed in situ by exposure to CO₂. This further confirms that the temperature increase is likely not the only explanation for the enhancement in the reaction rates. Rather, as corroborated by photophysical studies reported in the literature, we propose that illumination induces changes in the electron density of Ru partly covered by a thin layer of TiO_x, lowering the CO coverage, and thus enhancing the methane formation rate upon illumination. Full article

Recent catastrophic bridge fire incidents have highlighted the critical need for effective post-fire assessment of bridges, thereby challenging the dominant practice of complete replacement following these destructive events. This study investigates the post-fire performance of bare, isolated, and Carbon Fiber Reinforced Polymer (CFRP)-repaired Reinforced Concrete (RC) bridge columns under single-unit truck impact followed by air blast. This extreme loading scenario was deliberately selected given the increased vulnerability of bridge columns to this loading scenario in the recent few years. Three-dimensional Finite Element (FE) models of the structural system and surrounding environment were developed and validated in LS-DYNA. The effectiveness of two in-situ retrofitting schemes in mitigating damage and enhancing structural integrity of three column diameters under the selected multi-hazards was assessed. Results demonstrated that wrapping the bottom half of the column height prevents shear failure and significantly reduces the damage under the coupled impact and blast. In contrast, employing a combination of CFRP bars and externally bonded sheets showed limited enhancement on post-fire impact and blast performance. This study provides critical insights into the feasibility and efficacy of retrofitting bridge columns that have experienced fire, thus laying the groundwork for the reconsideration of current design and rehabilitation protocols. Full article

Improving the energy release and safety of composite solid propellants is a key focus in energetic materials research. Graphene, with its excellent thermal conductivity and lubrication properties, is a promising additive. In this study, Al@AP core–shell particles doped with graphene were prepared via an in-situ deposition method. The structure, thermal decomposition, combustion, and safety performance of the graphene-doped Al@AP samples were investigated. Results showed that AP effectively coated aluminium to form a typical core-shell structure, with graphene uniformly loaded into the framework. Graphene contents of 1.0 and 4.0 wt.% reduced AP’s thermal decomposition temperature by 0.97 and 16.68 °C, respectively. Closed-bomb and laser ignition tests revealed that pressure rise rates and combustion intensity increased with graphene content up to 1.0 wt.% but declined beyond that. Peak pressure reached 114.65 kPa at 1.0 wt.% graphene, and the maximum pressure increase rate was 13.29 kPa ms⁻¹ at 2.0 wt.%. Additionally, graphene significantly improved safety by reducing sensitivity to impact and friction. The enhanced performance is attributed to graphene’s large surface area and excellent thermal and electrical conductivity that promote AP decomposition and combustion, combined with its lubricating effect that enhances safety, though excessive graphene may hinder these benefits. This study provides balanced design criteria for graphene-doped Al@AP as solid propellants. Full article

This study designed Al_xCrFeNi (x = 0.8, 1.0, 1.2) medium-entropy alloys featuring a BCC + B2 dual-phase structure to systematically investigate the effects of Al content variation and heat treatment on microstructure evolution and corrosion behavior. Microstructural characterization revealed that all investigated alloys maintained the BCC + B2 dual-phase labyrinth structure. Electrochemical tests showed that as the Al content increased, the corrosion current density and corrosion rate in a 3.5 wt% NaCl solution increased. Synergistic analysis of post-corrosion morphology (through electrochemical testing and in-situ immersion) combined with XPS analysis of the passive films revealed that the initial stage of corrosion was primarily pitting. Subsequently, due to the loose and porous Al₂O₃ passive layer formed by the NiAl-rich phase, which was easily attacked by Cl⁻ ions, the corrosion progressed into selective corrosion of the NiAl phase. Notably, heat treatment at 1000 °C induced microstructural refinement with enhanced coupling between chunky and labyrinth structures, resulting in improved corrosion resistance despite a 4–6% reduction in Vickers hardness due to elemental homogenization. Among the investigated alloys, the heat-treated Al_0.8CrFeNi exhibited the most promising corrosion resistance. Full article

Precast concrete is an advanced construction technique characterised by high precision, quality, optimisation and is increasingly used in commercial and residential buildings. However, connections between precast elements are often constructed using in-situ casting, which can delay projects and complicate disassembly at the end of a structure’s service life. Dry connections, aligned with the principles of manufacture-to-assemble (MTA), offer a practical and sustainable alternative but present significant challenges regarding seismic performance, particularly in earthquake-prone regions. This study addresses these challenges through a comprehensive parametric numerical investigation into the shear capacity of precast walls with dry connections. Using SeismoStruct 2024 software, more than 340 pushover simulations were conducted to evaluate the influence of various parameters, including concrete compressive strength, axial force percentage, wall section height, overall wall height, and connection characteristics such as bar diameter, quantity, and placement. This research provides critical insights into the combined effects of these parameters, identifying optimal configurations to maximise shear capacity, which is a vital factor for seismic performance. Key findings indicate that shear capacity is significantly enhanced by increasing section height, concrete strength, and axial load, with notable gains such as an 84% improvement in shear strength when section height increased from 2 m to 3 m under favourable conditions. Conversely, increasing overall wall height tended to reduce shear capacity, with a 58% decrease observed for walls extending from 1.5 m to 3.5 m. Adjustments in mechanical connections, including larger diameters, increased bar quantities, and optimised placements, further contributed to incremental improvements in shear strength, with increases ranging from 3% to 24%. Full article

With the increasing demand for clean energy, in-situ hydrogen production from hydrocarbon reservoirs has attracted increasing attention. In this work, a nanoscale nickel catalyst was prepared using the water-in-oil (w/o) microemulsion method and applied in the in-situ generation of hydrogen-rich syngas from heavy oil reservoirs. The activation energy (Ea) of the gasification reactions significantly decreased with the addition of the nickel catalyst. The catalytic effect was monitored through remarkable increases in the peak temperature values for both the low-temperature oxidation (LTO) and high-temperature oxidation (HTO) processes, and the two peaks also shifted to lower-temperature regions. Additionally, the catalyst exhibited excellent activity and selectivity during the reaction process, and therefore the highest production rate of hydrogen-rich syngas of 20.07%, combined with the peak hydrogen concentration of 5.00%, was obtained in the presence of the catalyst and water. The substantial rate of hydrogen conversion from heavy oil was calculated to be 397.87 mL/g. The preliminary results obtained in this work show that this method is a significant improvement, and the catalyst-assisted method is believed to have great potential for underground fossil fuel conversion in the future. Full article

This paper adds to the sustainable materials field by in-situ epoxidation of rubber seed oil (RSO), a highly underutilized resource that has been sporadically used, using an optimized combination of 30% hydrogen peroxide and acetic/formic acid sulfuric acid. Most of the previous studies deal with more common vegetable oils, where the main focus in most is given to the epoxidation of these oils and their derivatives. The RSO contained a high iodine value around 135.36 g–I2/100 g. The central to this work is the systematic study of the oxirane number as a function of reaction temperature and the double bond:RCOOH:H₂O₂ molar ratios. By testing the temperatures of 40, 50, 60, and 70 °C and three specific molar ratios (1:0.6:1.4, 1:1:2, and 1:1.5:3), this research not only found the optimal conditions for epoxidation but also gave valuable information on the reaction kinetics of rubber seed oil. The results showed that a temperature of 60 °C with a 1:1:2 molar ratio gave the highest oxirane number, especially with performic acid, which was 3.200 mmol/g. Then, overall, formic acid consistently outperforms acetic acid in terms of product yields, facilitating a more effective epoxidation process. Full article

A small experimental setup for in-situ measurement of the load-transferring strains during the curing process of thermosets is proposed. Combining the output from an unconstrained and a kinematically constrained setup, it is possible to design a cure profile for the first time, lowering the residual stresses in the final product while keeping the cure time short based on the output from a few simple experiments. The stress relaxation during the curing process under a kinetically constrained condition is accounted for by comparing the final cure-induced strain during a kinetically unconstrained and constrained cure experiment. The constrained polymer is curing between two laminates where the constraining layer is removed after finalizing the cure profile, making it possible to measure the final cure-induced strain for that case as well. The temperature at which the load-transferring point is reached is found to be a key process parameter from which the final cure-induced strains can be predicted for the unconstrained case. From the corresponding constrained cure experiments, the final residual stresses can be measured. Full article

There is much promise for creating metal organic framework (MOF) films on metal substrates in fields including sensing and electrical conduction. For these applications, direct production of MOF films with strong bonding on metal substrates is extremely desirable. In this study, a simple one-step method without the need for additives or pre-modification is used to directly create zeolitic imidazolate framework-8 (ZIF-8) films with strong bonding on zinc substrate. The formation mechanisms of ZIF-8 film are analyzed. The strong bonding ZIF-8 film can be attributed to an in-situ grown ZnO interlayer between the ZIF-8 and substrate. The growth process shows the formation time of zinc oxide on the substrate, which is subsequently covered by ZIF-8 crystals. The ZnO interlayer results from a combination of decomposition products of the solvent and the zinc ions. Furthermore, the ZnO interlayer serves as a sacrificial precursor for the in-situ nucleation and continuous growth of ZIF-8 film. It serves as an anchoring site between ZIF-8 film and substrate, resulting in strong adhesion. This paper describes a simple and straightforward production process that is expected to provide a theoretical basis for the laboratory preparation of ZIF films. Full article

Coastal zones, particularly sandy beaches, are highly dynamic environments subject to a variety of natural and anthropogenic forcings. Instantaneous shoreline is a widely used indicator of beach changes in image-based applications, and it can display undulations at different spatial and temporal scales. Megacusps, periodic seaward and landward shoreline perturbations, are an example of such undulations that can significantly modify beach width and impact its usability. Traditionally, the study of these phenomena relied on video monitoring systems, which provide high-frequency imagery but limited spatial coverage. Instead, this study explored the potential of employing multispectral satellite-derived shorelines, specifically from Sentinel-2 (S2) and PlanetScope (PLN) platforms, for characterizing and monitoring megacusps’ formation and their dynamics over time. First, a tool was developed and validated to guarantee accurate shoreline detection, based on a combination of spectral indices, along with both thresholding and unsupervised clustering techniques. Validation of this shoreline detection phase was performed on three micro-tidal Mediterranean beaches, comparing with high-resolution orthomosaics and in-situ GNSS data, obtaining a good subpixel accuracy (with a mean absolute deviation of 1.5–5.5 m depending on the satellite type). Second, a tool for megacusp characterization was implemented and subsequent validation with reference data proved that satellite-derived shorelines could be used to robustly and accurately describe megacusps. The methodology could not only capture their amplitude and wavelength (of the order of 10 and 100 m, respectively) but also monitor their weekly–daily evolution using different potential metrics, thanks to combining S2 and PLN imagery. Our findings demonstrate that multispectral satellite imagery provides a viable and scalable solution for monitoring shoreline megacusp undulations, enhancing our understanding and offering an interesting option for coastal management. Full article

Formaldehyde (HCHO) is known as one of the important indoor organic pollutants. How to remove and decompose the low concentration of formaldehyde at room temperature is important for indoor environments. Catalytic ozonation is an efficient method to thoroughly remove HCHO at room temperature, with high efficiency and few byproducts. A series of MnO_x/γ-Al₂O₃ catalysts were prepared in this work via the impregnation method and treated with different reagents (acid, alkali, and H₂O₂) to evaluate their catalytic activity for HCHO removal. The results showed that MnAl-II (acid treatment) performed well in activity tests, reaching a nearly 100% HCHO conversion at an O₃/HCHO of 2.0 and attaining a CO₂ selectivity of above 95% at an O₃/HCHO of 3.0 at 30 °C, with almost no ozone residual existing. The larger specific surface area, abundant oxygen vacancies, and higher number of acid sites contributed to the excellent performance of MnAl-II. Stability and H₂O resistance tests of MnAl-II were also conducted. To reveal the intermediate product formation and further investigate the reaction mechanism of HCHO ozonation, in-situ DRIFTS measurement was carried out combined with DFT calculations. Full article

Daya Bay, a semi-enclosed bay in the northern South China Sea and to the east of the Pearl River Estuary, is rich in biological resources and diverse habitats. Current research on mesozooplankton in Daya Bay has mainly focused on aspects such as species composition, biomass, and biodiversity in the zooplankton community. However, there is limited research on the top-down effects of mesozooplankton on prey communities. This study conducted seasonal in-situ cultivation experiments from 2015 to 2017. By combining mesozooplankton grazing experiments and microzooplankton dilution experiments, the mesozooplankton clearance rate and trophic cascading effect on low trophic levels were calculated. Results showed evident mesozooplankton selective feeding behavior and corresponding trophic cascades with seasonal variations, these being significantly higher in the spring and summer and lower in the autumn and winter. Different sizes of phytoplankton showed significant differences; large-sized phytoplankton received high feeding rates but low trophic cascades by mesozooplankton, while the opposite was true for small-sized phytoplankton. Trophic cascades contribute in three ways: offsetting direct grazing mortality, changing prey community structure via its effects on different phytoplankton sizes, and reducing ciliate grazing impacts at an average of 14.4 ± 7.8%, maintaining around 70% ciliate grazing impacts in nature. The composition of mesozooplankton was the primary reason for explaining feeding preferences, including size selectivity and omnivory. For instance, high cladoceran abundance caused high feeding rates while, on the other hand, high omnivorous copepods abundance caused high trophic cascades on small-sized phytoplankton. General additive model (GAM) analysis revealed that the changes in trophic cascades were highly dependent on temperature, ciliate abundance, mesozooplankton feeding rates on ciliates, and ciliate feeding rates on phytoplankton. The significance of this study lies in its contribution to providing valuable insights into the role of mesozooplankton in the marine food web and their impact on lower trophic levels. In addition, the findings can help inform the management and conservation of marine ecosystems, as well as guide future research in this field. Full article